THIS IS A PRESERVE FOR PEOPLE WHO LIKE THE marriage of sweet and tart. The orange plays with the rhubarb beautifully and the sugar serves as flavor brightener as much as sweetener. I particularly like it stirred into Greek yogurt and topped with toasted walnuts. Occasionally, I’ll add a bit of ground cardamom to really good effect. Because this is a stovetop butter, it requires a bit more tending than ones made in the oven or slow cooker. It’s great for those days when you’ve got multiple kitchen projects going, so that the regular stirring doesn’t feel like a chore. If it starts to splash over your stove, top the pot with a splatter shield so that it can continue to cook down without making a mess.
8 cups chopped rhubarb (about 3 pounds/1.4 kg rhubarb)
2 cups/400 g granulated sugar
2 cups/480 ml orange juice
Combine the rhubarb, sugar, and orange juice in a large, heavy saucepan and bring to a simmer. Reduce the heat to low and let it gently bubble, stirring every 5 minutes or so. If it’s sticking to the bottom of the pot, lower the heat a bit more. Continue cooking like this for at least an hour, until the butter has reduced in volume and has turned a deep, rosy color.
Thirty minutes before the butter is finished, prepare a boiling water bath and 2 regular-mouth 1-pint/500 ml jars according to the process on page 10. Place the lids in a small saucepan, cover them with water, and simmer over very low heat.
When the butter is done, remove the pan from the heat and ladle the butter into the prepared jars. Wipe the rims, apply the lids and rings, and process in a boiling water bath for 15 minutes (see page 11).
The sealed jars can be stored in a cool, dry place for up to 6 months.