1 gallon chokecherries
1 teaspoon cream of tartar
8 cups organic cane sugar
Wash and pick over the chokecherries. Put them in a large pot and add water, but do not completely cover the fruit. Simmer the cherries for about 1 hour, until they are soft. Check occasionally to make sure the water level stays just below the top of the fruit.
Strain the mixture into a clean cooking pot, removing the pulp and pits and squeezing out some of the cherry juice. Add cream of tartar to juice.
Heat the juice slightly, then stir in sugar. Cook over medium-high heat, stirring constantly, until the juice comes to a boil. Continue stirring, cooking the mixture at a full boil for at least 1 minute. Remove from heat.
Carefully fill canning jars with hot chokecherry syrup, leaving about 1/2-inch headspace in each. Cap the jars tightly.
Fit a canning pot with a wire rack, and fill it halfway with boiling water. Use tongs to position jars on the rack, making sure there’s plenty of room between each. When all the jars are in place, add more boiling water, pouring the water down the side of the pan, not directly onto the jars. Be sure to cover the jars with at least 2 inches of water.
Cover the pot with a tight lid and bring the water to a full rolling boil. Reduce the heat, but maintain a rapid boil. Check the water level regularly, adding boiling water as needed to keep the jars completely covered.
Boil for 15 to 25 minutes, depending on your altitude. (See tip below for ensuring the correct cooking time.)
Use oven mitts and tongs to remove each jar. Set them on a rack or on several layers of towels to cool. Check the seal when the jars are completely cooled.