To achieve this plum jam nirvana, start with good fruit. It doesn’t have to be precious stuff — save that for eating fresh — but find fragrant plums and pluots. That’s obvious. This next trick, less so. Start by cooking down the fruit before adding the sugar. It intensifies the fruit’s flavor and prevents the sugar from overcooking into unwelcome burnt bitterness. Once the sugar goes in, it liquefies into the plums’ juices and caramelizes just enough to deepen the plummy-ness while keeping the flavor fresh.
Birthday Plum Jam
Put 3 metal spoons in the freezer. Combine the plums, lemon juice, salt and 1 tablespoon water in a medium saucepan. Bring to a simmer over medium heat, stirring occasionally. Reduce the heat to medium-low and simmer, stirring occasionally, until the fruit starts to soften a little, about 3 minutes.
Stir in the sugar. Bring the mixture to a boil over medium-high heat, stirring occasionally. Reduce the heat to maintain a steady low boil. Continue boiling, stirring and skimming off foam from the surface occasionally, until the mixture is thickened and drizzly like maple syrup, 12 to 15 minutes. To test the jam’s doneness, take a spoon from the freezer and scoop a little onto the tip. Tilt the spoon; the jam should glide as slow as honey. Repeat the testing with the remaining spoons if needed.
Divide the jam among three clean half-pint canning jars. Seal and cool to room temperature, then refrigerate.