½ lb. fresh, ripe fruit (strawberries, raspberries, peaches, blueberries, etc.)
If needed, peel and pit the fruit; cut into small pieces. Puree the fruit by whirling it in a blender or food processor or forcing it through a food mill. Or simply mash it with a potato masher as you cook it down.
Place the pureed fruit into a heavy-bottom saucepan. Turn the heat to medium and, stirring almost constantly, heat the fruit to a bare simmer. Reduce the heat and continue to cook the fruit, stirring almost constantly so the bottom doesn’t scorch, until it reaches a thick, jam-like consistency.
The jam will keep in the refrigerator for about a week, so if you make more than you can use in that time, freeze the rest. When you pull it out of the freezer to thaw, whisk the jam to re-emulsify.
Yield varies.
Note: Using this cook-down method, you can make as much or as little jam at one time as you want to.