Simmering the cherries before adding the other ingredients helps to create a juicier, more spreadable jam. If the fruit separates in the jars, wait until they have sealed and cooled (about one hour) and then shake or roll them very gently to redistribute the fruit.
- 2 1/4 cups granulated sugar
- 2 1/4 teaspoons Pomona's Universal Pectin
- 3 pints sour cherries
- 1 tablespoon freshly squeezed lemon juice
- 3 teaspoons calcium water (included in the Pomona's packet)
- 1/4 teaspoon unsalted butter
Combine the sugar and pectin in a medium bowl.
Pit the cherries and transfer them to the work bowl of a food processor. Pulse the cherries 8 to 10 times, until they are coarsely chopped but not pureed. Measure 4 cups of the cherry puree and transfer to a large, heavy bottomed pot. (Discard any remaining cherries or reserve for another use.) Add the lemon juice and bring to a simmer. Simmer, stirring occasionally, until the cherry pieces have softened and are beginning to break down, about 10 minutes.
Stir the calcium water and the butter into the pot with the cherries and bring the mixture to a boil. Add the sugar-pectin mixture and return the mixture to a boil, stirring constantly. Boil hard for one minute.
Remove the pot from the heat and skim any foam from the surface of the jam with a cold metal spoon. Ladle the jam into hot sterilized jars and process them in a hot water bath for 10 minutes.