When you have an abundance of juicy sweet Concord grapes, this superb jelly is quick to make and sings of grape flavor.
How to Make It
Put the grapes and apple in a large pot and add 1/2 cup of water. Bring to a boil, cover and simmer over low heat until very juicy, about 10 minutes. Strain the juice through a fine sieve set over a large bowl.
Strain the juice again through several layers of dampened cheesecloth, without pressing or squeezing; you should have 3 cups.
In a very large saucepan, boil the grape juice and sugar over moderate heat, stirring, until the jelly falls off a cool spoon in sheets and registers 220° on an instant-read thermometer, about 18 minutes.
Pour the jelly into hot, sterilized canning jars to within 1/4 inch of the rims. Seal. Submerge the jars in a pot of water and boil for 5 minutes. Carefully remove the jars and let cool. Check the jar lids to make sure they’ve fully sealed; refrigerate any jars with imperfect seals.