Jam Session

Plums and Pluots

Some fruits are more interesting when used in condiments rather than prepared as a simple jam. Plums are like that. Plums tend to be tart and rather monochromatic until you add a bit of sugar. Sure, you can add anise or ginger to make them a bit more distinctive, but their powerful tartness will always dominate. However, when it comes to using plums in condiments and chutneys, you hit the jackpot. Because of their tart versatility, they pair well and hold up to other strong flavors. Russian and Georgian plum condiments are eaten with fried chicken or lamb, and Asian-inspired plum sauce is served with duck and pork spareribs. In Italian wine bars, spiced plum condiments are served as accompaniments to cheese plates. And plums make a great mostarda to serve with roast meats and poultry or even to enliven boiled beef or tongue.

For dramatic color, I prefer to use plums that are red on both the outside and inside, but for flavor, plums with yellow flesh will work, too. Japanese plums dominate the start of the season, followed by European varieties.

Japanese plum varieties with red flesh include Burgundy, Elephant Heart, and Satsuma.

Japanese varieties with amber flesh are Friar, Laroda, Mariposa, Santa Rosa, and Casselman.

Japanese green plums are Kelsey and Emerald Beauty.

European plum varieties, such as Italian prune plums, are smaller than Japanese ones, and are oval with purple-blue skin and yellow flesh. French prunes, the gages, and damson plums are also in this category. The Italian prune plums are meatier than the French ones and have a distinct seam so they are easier to cut, pit, and prepare.

We don’t see damsons at my San Francisco market very often, so when local grower Blossom Bluff had them for sale, I jumped at the opportunity to preserve them. Their tart flesh is yellow but when cooked turns a remarkable shade of burgundy red, almost maroon. Because they are so small and difficult to pit, they require another cooking technique altogether from the other plums.

As for their name, damsons were supposedly first cultivated around Damascus in antiquity, and the Romans may have brought them to England. However, I have not found any Syrian recipes that use this plum, so this may just be a story to lend them mystique. It is more likely they are related to the tart, round bullace plums, such as the sloe or cherry plums

Let’s start with an optimistic but unlikely premise: If the damsons are firm-ripe enough for you to pit them before cooking, do so, because the process will be less messy in the end. But this is a rare occurrence, so most recipes recommend cooking them whole, gently, in water for 45 minutes to 1 hour, until they break down. Then let them cool until you can handle them and pick out the pits with your fingers. It will look as if some terrible carnage has taken place in your kitchen, but you need to get rid of those pits! After you have removed all the pits, you can then put the pulp through a food mill or pulse it in a food processor, much as you do when preparing quince for jam, jelly, or membrillo. Even after cooking and pureeing, a few of those tiny pits always show up.

Damsons make an elegant jam, an excellent plum butter, and a really fine jelly. When cooked long enough, they will also set up into a firm paste that resembles membrillo. Oddly, in England this paste is called damson cheese, which to my mind is an unfortunate name, as it is served with cheese.

The pluot is part of a family of hybrids that includes plumcots, apriplums, and apriums. They are a cross between a plum and an apricot. The first-generation hybrids were the plumcot and apriplum. The pluots and apriums are later generations. The pluot, in my mind, is the most successful of all the crosses. Genetically speaking, pluots are one-quarter apricot and three-quarters plum. They were developed by Floyd Zaiger. The aprium is one-quarter plum and three-quarters apricot.

The most popular and tasty pluots are the Flavor King and Dapple Dandy. They may be used in preserving, but I think plums are a bit richer and tarter in flavor.

Flavor affinities for plums are anise, cinnamon, cloves, ginger, vanilla, orange, lemon, mint, basil, walnuts, black pepper, and pomegranate.

Although you can use water, using prune or pomegranate juice amplifies the flavor of the plums.

In a large preserving pot, gently combine the plums, sugar, and lemon juice and toss to mix. Let sit overnight to macerate.

If the plums have not given off at least ½ cup of liquid by the next day, add the prune juice, pomegranate juice, or water.

Bring the plum mixture to a simmer over medium-low heat, stirring frequently and cooking until the fruit is very soft and the jam thickens.

Place a baking sheet on the counter near your stove. Heat a kettle of water. Set two stockpots on the stove and fill them with enough water to cover the jars by 1 to 2 inches. Bring the water to a boil over medium-high heat. Sterilize the jars (see this page) in the water bath.

For a smooth texture, puree the cooked fruit with an immersion blender or mash with a potato masher. Continue to cook the mixture, stirring frequently, over medium-high heat until it coats the back of a wooden spoon and passes the plate test (see this page), achieving a soft set that is a bit runny. Watch closely because this jam sets up really thick, even if it tests sort of runny. Opt for a looser set. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheet.

Ladle the jam into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using a jar lifter, gently lower the jars into the pots. When the water returns to a boil, decrease the heat to an active simmer, and process the jars for 10 minutes. Turn off the heat and leave the jars in the water for 1 to 2 minutes.

Using the jar lifter, transfer the jars from the pots to the baking sheet and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed jam for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

Because plums are so assertively tart, they need a hefty amount of ginger for its presence to be known.

Peel the ginger and slice thin. Grind the ginger in the food processor. You want about 1 cup of ginger puree.

In a large preserving pot, gently combine the plums, sugar, ginger, and lemon juice and toss to mix. Let sit overnight to macerate. (If you do not have time to macerate, then add the prune juice along with the lemon juice.)

Bring the jam to a boil over medium-high heat and cook, stirring frequently, until the jam thickens and coats the back of a wooden spoon. Taste and add a squeeze more lemon juice, as needed. Do the plate test (see this page). The jam should be a soft but slightly runny set. Watch closely because this jam sets up really thick, even if it tests sort of runny. Opt for a looser set. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheet.

Ladle the jam into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

In a large preserving pot, gently combine the plums, sugar, prune or pomegranate juice, lemon juice, star anise, black pepper, and five-spice powder and toss to mix.

Bring the plum mixture to a boil over medium-high heat and cook, stirring frequently, until the jam thickens. Taste and adjust the seasoning, adding a squeeze more lemon juice or more pepper, if needed.

When the jam coats the back of a wooden spoon, do the plate test (see this page). You want a soft set that mounds on the plate and is neither runny nor stiff. Watch closely because this jam sets up really thick, even if it tests sort of runny. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheet.

Ladle the jam into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

For this conserve, I prefer firm, red plums that are red all the way through, such as Burgundy or Elephant Heart, but Santa Rosa or even Italian prune plums will work, too. Walnuts and pomegranates are used extensively in preserves in the Balkans and Caucasus. Note that this recipe uses two forms of pomegranate—juice and molasses. The addition of walnuts and raisins turns this condiment into a conserve.

4 pounds tart plums, preferably Burgundy, Santa Rosa, or Elephant Heart, but prune plums will also work

Cut the unpeeled lemons into quarters, remove any seeds, and place the quarters in the bowl of a food processor. Pulse until pulverized.

In a large preserving pot, gently combine the plums, lemons, pomegranate juice, sugar, coriander, cinnamon, allspice, Maras or Aleppo pepper, and salt and toss to mix.

Place two baking sheets on the counter near your stove. Heat a kettle of water. Set two stockpots on the stove and fill them with enough water to cover the jars by 1 to 2 inches. Bring the water to a boil over medium-high heat. Sterilize the jars (see this page) in the water bath.

Bring the conserve to a boil over medium-high heat, decrease the heat, and simmer until the plums are tender, 10 to 20 minutes. Add the raisins, black pepper, pomegranate molasses, lemon juice, and mint. Continue to simmer, stirring frequently (to prevent the raisins from sinking and scorching), until the mixture thickens.

Taste and adjust the tart-sweet ratio, adding more sugar or lemon juice, as needed. Stir in the walnuts. Taste once more to check the salt level and add more if needed. Do a plate test (see this page). The conserve should mound on the plate and not be runny. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the conserve into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed conserve for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

I first tasted a version of this condiment served alongside a cheese assortment in an Italian wine bar, and so it seemed logical to use Italian prune plums for the recipe. If you can’t find them in your market, any other plum will work.

In the style of the Italians, I like to serve this jam with a cheese course. The slightly peppery prune plum sauce is especially good with robiola cheese and a glass of Amarone. Of course it is delicious with roast pork and chicken, too.

Cut the unpeeled oranges into quarters, remove any seeds, and place the quarters in the bowl of a food processor. Pulse until pulverized.

In a large preserving pot, gently combine the plums, orange pulp, and water or juice and toss to mix.

Bring to a boil over medium-high heat, decrease the heat to low, and simmer until the plums are very soft.

Return the puree to the pot. It will be soupy. Add the sugar and lemon juice to taste and simmer over medium heat, stirring frequently, until it coats the back of a spoon and passes the plate test (see this page), achieving a soft set that is neither runny nor stiff. Stir in the pepper and salt. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the jam into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed jam for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

The mustard powder–mustard seed combination in this recipe is my attempt to come close to Italian mustard oil. It does not have the same degree of bite and heat, but it is pleasingly hot and sweet, which is the ultimate goal of a mostarda.

Surprise yourself and serve this condiment with poached or baked salmon. It is also good on porchetta, roast pork, chicken, and that bland old turkey. Or add it to ham sandwiches or charcuterie assortments.

Halve and pit the plums, quartering or slicing the halves if large. You will have about 8 cups.

Cut the unpeeled orange into quarters, remove any seeds, and place the quarters in the bowl of a food processor. Add the ginger and ½ cup of the vinegar. Pulse until pulverized.

In a large preserving pot, gently combine the plums, orange-ginger mixture, remaining 1½ cups vinegar, lemon zest and juice, sugar, mustard seeds, mustard powder, salt, black pepper, and cayenne, and toss to mix.

Bring the mostarda to a boil over medium-low heat. Decrease the heat to medium and cook, stirring frequently, until the mixture thickens and passes the plate test (see this page), achieving a soft set that is neither runny nor stiff. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the mostarda into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed mostarda for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

This Russo-Georgian plum sauce is traditionally served with tabaka, a sour cream and buttermilk-marinated fried chicken, but I have found that tkemali is good with all lamb and poultry kebabs, pork chops, roast pork, roast chicken, turkey, and lamb, as well as poached or grilled salmon. The herbs and heat make this sauce distinctive. As a variation, increase the cilantro or use mint or tarragon instead of basil. They love tarragon in the Caucasus.

4 cups granulated sugar or white sugar or 5 cups firmly packed light brown sugar

Cut the unpeeled lemons into quarters, remove any seeds, and place the quarters in the bowl of a food processor. Pulse until pulverized.

In a large preserving pot, gently combine the plums, lemons, garlic, prune or pomegranate juice, vinegar, sugar, cayenne, allspice.

Bring to a boil over medium heat, decrease the heat and simmer, stirring frequently. When the mixture reaches sauce consistency, stir in the basil, cilantro, and black pepper and simmer for 5 minutes.

Taste and add the lemon juice and additional salt, if needed. The sauce should be tart. Continue to simmer, stirring frequently, until the mixture passes the plate test (see this page), achieving a soft set. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the sauce into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed sauce for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

Prick each plum with a toothpick or paring knife (so they don’t explode during cooking).

Combine the port, sugar, water, and orange juice in a medium nonaluminum saucepan. Bring to a boil over medium-high heat and boil for 3 minutes, stirring to dissolve the sugar. Add the cinnamon stick, vanilla bean, and orange peel and continue to boil for 5 minutes. Decrease the heat to medium-low.

When the poaching syrup is simmering, add the plums and simmer for 8 minutes. Turn off the heat and let sit overnight in a cool place.

The next day, place a baking sheet on the counter near your stove. Heat a kettle of water. Set a stockpot on the stove and fill it with enough water to cover the jars by 1 to 2 inches. Bring the water to a boil over medium-high heat. Sterilize two wide-mouth pint jars (see this page) in the water bath.

Bring the plums and syrup to a boil over medium-high heat. Reduce the syrup by one-quarter as it thickens.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheet.

Using a slotted spoon, distribute the plums evenly between the jars. Ladle the syrup into the jars over the plums, leaving 1-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using a jar lifter, gently lower the jars into the pot. When the water returns to a boil, set the timer for 15 minutes, decrease the heat to an active simmer, and process the jars. Turn off the heat and leave the jars in the water for 1 to 2 minutes.

Using the jar lifter, transfer the jars from the pot to the baking sheet and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label the sealed plums and let rest for 4 to 6 weeks before eating, then store for up to 1 year. Once open, store in the refrigerator for up to 1 week.

This homemade version is not as colorful as the electric-pink sauce served in your neighborhood Chinese restaurant, but it’s twice as complex in flavor.

Just as you would enjoy it at the restaurant, serve it with barbecued pork or spareribs. It’s also good with sautéed duck breast and even grilled fish.

Halve and pit the plums, and cut the flesh into ½- to ¾-inch dice. You will have about 8 cups.

In the bowl of a food processor, combine the onion, garlic, ginger, cinnamon, allspice, five-spice powder, star anise, and apples. Pulse until pulverized and then pulse again with 1 cup of the vinegar.

In a large preserving pot, gently combine the plums, the pulverized spice mixture, remaining 1 cup of the vinegar, sugar, and salt, and toss to mix. Bring to a boil over medium-high heat.

Cook the sauce, stirring frequently, over medium-high heat until it thickens and passes the plate test (see this page), mounding on the plate and not runny. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the sauce into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed sauce for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

Plums work so well in many condiments, making them a natural base for a tangy chutney.

In a small bowl, combine the raisins and water or juice and set aside for 5 minutes to plump.

In a large preserving pot, combine the plums, raisins and plumping liquid, vinegar, apples, onion, garlic, chiles, cinnamon, allspice, cloves, ginger, salt, and sugar and toss to mix.

Bring to a boil over medium-high heat, then decrease the heat to medium-low and simmer, stirring frequently, until the chutney thickens, about 30 minutes.

Do a plate test (see this page). The chutney should mound on the plate and be syrupy.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the chutney into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed chutney for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

Allow these to mellow for about a month in the jar before you serve them as a sweet and tart condiment for charcuterie and other salumi.

Prick each plum with a toothpick or paring knife (so they don’t explode during cooking).

Combine the sugar and vinegar in a medium nonaluminum saucepan. Bring to a boil over medium-high heat and boil for 3 minutes, stirring to dissolve the sugar. Add the cinnamon sticks and cloves and continue to boil for 3 more minutes. Decrease the heat to medium-low.

When the poaching syrup is simmering, add the plums and simmer for 3 minutes. Turn off the heat and let sit overnight in a cool place.

Place a baking sheet on the counter near your stove. Heat a kettle of water. Set a stockpot on the stove and fill it with enough water to cover the jars by 1 to 2 inches. Bring the water to a boil over medium-high heat. Sterilize the jars (see this page) in the water bath; leave in the water to keep warm. Simmer the lids in a saucepan of hot water.

Reduce the syrup by one-quarter. Spoon the hot syrup into the jars over the plums, leaving 1-inch headspace. Wipe the rims clean and set the lids over the mouths of the jars. Twist on the rings.

Using a jar lifter, gently lower the jars into the pot. When the water returns to a boil, decrease the heat to an active simmer, and process the jars for 15 minutes. Turn off the heat and leave the jars in the water for 1 to 2 minutes.

Using the jar lifter, transfer the jars from the pot to the baking sheet and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed plums for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

Italian prune plums are traditionally used for this rich German plum butter, but you could use damsons instead. For the final thickening, you can cook this on stove top or in the oven.

Plum butter is traditionally used as a filling for pastries and dumplings, and spooned on potato pancakes. It pairs well with butter, mascarpone, or clotted cream on toast, biscuits, or crepes. You can also spoon some atop soft polenta with mascarpone or ricotta. Not very German, but very good.

1 teaspoon Chinese five-spice powder, or ½ teaspoon ground cloves and ½ teaspoon ground cinnamon, plus more as needed

In a wide, shallow preserving pot, combine the prune plums, 2 cups of the sugar, the lemon juice, five-spice powder or cloves and cinnamon, and the vanilla extract, and toss to mix. Let sit overnight to macerate.

Cook the plum mixture on the stove top over medium heat. When the plums are very soft, remove from the heat and set aside to cool to warm. Puree with a stick blender or food mill or in a food processor. Transfer the puree to the preserving pot.

Bring the puree to a simmer over low heat. Taste, and if you think the mixture needs sweetening, add the remaining 1 cup sugar, stirring with a wooden spoon. Let the mixture cook, stirring frequently until it thickens. Taste and adjust the seasoning, adding a bit more lemon juice, five-spice powder or cloves and cinnamon, and/or a few drops of vanilla extract.

If you prefer, instead of standing at the stove and stirring, you may complete the cooking in a 300°F oven; cook uncovered for about 1 hour, stirring the mixture every 10 to 15 minutes.

While the mixture thickens, place a baking sheet on the counter near your stove. Heat a kettle of water. Set two stockpots on the stove and fill it with enough water to cover the jars by 1 to 2 inches. Bring the water to a boil over medium-high heat. Sterilize the jars (see this page) in the water bath.

Continue to simmer the mixture (or cook in the oven), stirring frequently, until the mixture thickens and passes the plate test (see this page), mounding on the plate. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheets.

Ladle the pflaumenmus into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

Using a jar lifter, gently lower the jars into the pots. When the water returns to a boil, decrease the heat to an active simmer, and process the jars for 15 minutes. Turn off the heat and leave the jars in the water for 1 to 2 minutes.

Using the jar lifter, transfer the jars from the pots to the baking sheets and let sit for at least 6 hours, until cool enough to handle. Check to be sure the jars have sealed (see this page). Label and store the sealed pflaumenmus for 6 months to 2 years. Once open, store in the refrigerator for up to 3 months.

This very delicious jam is worth the mess. I like a bit of cardamom as a seasoning. Mild fresh ginger and orange juice and zest might be added as well. These plums are so hard to find—unless you have a tree—that you might want to be a purist and not add any flavorings to them.

Serve the jam on toast. It is especially good paired with cream cheese or other soft cheeses.

Stem, halve, pit, and quarter the plums, if possible. If you cannot pit the plums, just stem them.

In a small saucepan over medium-low heat, combine the water and plums. Cook until the plums are very soft. Turn off the heat and let sit to cool.

Process the plums through a food mill, or puree in a food processor. Measure the pulp. You should have 3 to 4 cups, but note the exact amount because that determines the amount of sugar you will need to use for this recipe.

Transfer the puree to a large preserving pot, and add the sugar. Stir in the lemon juice and cardamom.

Bring the plums to a simmer over medium heat and cook, stirring frequently, until the jam thickens and passes the plate test (see this page), achieving a soft set that is a bit runny. These plums are pectin bombs, so the jam will set up rather quickly. Remove the pot from the heat.

Bring the water bath back to a boil. If the jars have cooled, warm them in the water bath or in a 200°F oven. Simmer the lids in a saucepan of hot water. Place the jars on the baking sheet.

Ladle the jam into the jars, leaving ¼-inch headspace. Wipe the rims clean and set the lids on the mouths of the jars. Twist on the rings.

— For Damson Plum Butter: Double the Damson Plum Jam recipe, cooking 6 pounds of plums and sterilizing 8 or 9 half-pint jars. Combine the fruit puree, sugar, and lemon juice. Heat the puree slowly, stirring frequently, over medium to low heat. After 15 to 20 minutes of cooking, you may want to use a splatter screen if the mixture pops much. Continue cooking, stirring frequently, over low heat, until very thick. You may also complete this butter in the oven, as explained in Pflaumenmus (this page). Process the jars for 15 minutes in the water bath. From 6 pounds of Damsons, sometimes I get 6 cups of puree; other times I get 8 cups. The variance depends on the size of the plums and the ratio of pit to flesh. As for the amount of sugar needed,  ratios vary in recipes, but the average is about equal parts sugar to puree.

— For the membrillo-like Damson Plum Paste: Add 2 to 3 teaspoons grated ginger to the plum jam and cook the mixture until it is so thick that your spoon leaves a trail on the bottom of the pot when dragged through. Line two 8-inch baking pans with parchment paper and coat with cooking spray. (An 8-inch pan holds about 4 cups of plum paste.) Alternatively, lightly oil four half-pint jars (which you will seal and process as you do for the plum butter). Ladle half of the puree into one pan; it should be about 1 inch deep. Ladle the remaining puree into the other pan. Let sit at room temperature until it sets up, about 24 hours. When fully set, wrap the paste completely in parchment, place in a plastic container with a tight-fitting lid, and store in a cool place for 1 to 2 years.