The procedure in Kat's rhubarb jam can be applied to any fruit and any recipe. Lay your fruit evenly in a heavy baking dish—glass or glazed earthenware are best for slow, even heating without scorching—and stir in sugar, salt, and other flavorings. Kat adds orange zest and vanilla bean to her jam, along with some rosewater once it's done, but go nuts with your own favorite flavors. Then bake in a moderate oven, 350 degrees or so, for about an hour, until the fruit is very soft and the surrounding juices have turned into a thick syrup. You're looking for bubbles that stack on each other, a sign that you've cooked out enough water, and fruit soft enough that it collapses when prodded with a fork.