by Rachel Saunders of The Blue Chair Jam Cookbook
(makes about five 8-oz jars)
3.5 lbs fresh blackberries
3 oz strained freshly squeezed lemon juice
1 ¾ lbs cane sugar
Combine berries, sugar and lemon juice in a bowl and toss thoroughly. Transfer the mixture to a wide- bottomed pot like a Dutch oven or jam pan. Heat slowly, gently stirring, until the sugar dissolves and the berries begin releasing their juice. Turn the heat up high and cook, stirring frequently.
Test for doneness using the Freezer Test about 15-20 minutes from the time it reaches a rolling boil. Once a “set” is achieved, turn off the heat and do not stir. Skim any foam from the surface. Pour the jam into sterilized jars and process by water bath canning, oven canning, or refrigerate.