American plums feel like an endangered species. The now-famous 1911 publication from the New York Agricultural Experiment Station — a 600-page book called Plums of New York — illustrated so many more varieties of plums than we can find today. The other tragedy is that plums sold in supermarkets are picked so green that they don’t ripen into the depth of flavor of slightly warm summer fruit just off the tree. But here we are fortunate to have farmers markets and a few family businesses that have fruit orchards with variety. While the fruit is of different degrees of ripeness and not always perfect, it is so much better than the industrialized stuff. I purchase redheart plums from the same farmer every year. After we’ve had our fill of the raw fruit, it’s jammed just plain or paired with a seasonal companion like the plentiful red raspberries we pick every week at our CSA farm. This is a special jam, bright and slightly tart with a distinctive plum taste, sparked by raspberries.
Redheart Plum and Raspberry Jam
2 lbs redheart or other red plums
¾ c water
Approximately 2 c sugar
½ pt red raspberries
Wash the plums and cut the flesh from the pits, chopping it into 1/2-inch pieces. Place in a large pan with water and bring to a simmer over medium heat. Lower the heat and cook slowly until the plums are very soft, about 15 minutes. Cool slightly and puree with an immersion blender (or use a food processor) to break up the plum skin. Measure the liquid and combine with sugar in an amount equal to half of the volume of plums (4 c plum puree to 2 c sugar, for example). Stir well to dissolve the sugar and set aside for an hour or two, or longer, covered, in the refrigerator. Stir it every so often to dissolve the sugar. (I use a crinkled piece of parchment paper but use plastic wrap if the smell of the refrigerator contents might taint the jam.)
When ready to make the jam, prepare jars for water bath canning. Place a saucer in the freezer to test the gel.
In a large wide pan, combine the plum mixture with raspberries and being to a boil over medium high heat, stirring to prevent scorching. Continue to cook until the gel point is reached, about 7 minutes. Test for gel by placing a drop of the jam onto the frozen saucer; if it wrinkles to the touch, it’s gelled. Pour into the prepared jars, cap with two-part lids that have been immersed in boiling water, and process for ten minutes after the water in the canner returns to a boil. Turn off the heat, remove the canner lid and let sit for 5 minutes before removing to a counter to sit, undisturbed.
Makes about 8 four-ounce jars or 4 eight-ounce jars.