Apple-Blackberry Jam

Combine blackberries with 1/3 of the water in a saucepan over low heat. Combine apples with the remaining water and lemon juice in another saucepan over low heat. Simmer both pans slowly until blackberries and apples are soft and mushy, about 90 minutes.

Inspect twelve 12-ounce jars for cracks and rings for rust, discarding any defective ones. Immerse in simmering water until jam is ready. Wash new, unused lids and rings in warm soapy water.

Remove blackberries from the heat and pass through a sieve to remove the seeds, if desired.

Remove apples from the heat and puree with an immersion blender.

Combine pureed blackberries and apples in a large bowl and weigh on a scale. Add the same amount of sugar as the weight of the pureed fruit.

Transfer fruit puree and sugar to a large pot and bring to a boil. Cook at a rolling boil for 3 to 4 minutes. Test for the setting point by placing a dollop of the jam onto a cold plate and pushing it with your finger. If the jam wrinkles it is ready.

Pack jam into hot, sterilized jars, filling to within 1/4 inch of the top. Run a clean knife or thin spatula around the insides of the jars to remove any air bubbles. Wipe rims with a moist paper towel to remove any residue. Top with lids and screw rings on tightly.

Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars 2 inches apart into the boiling water using a holder. Pour in more boiling water to cover jars by at least 1 inch. Bring to a rolling boil, cover, and process for 15 minutes.

Remove the jars from the stockpot and let rest, several inches apart, for 12 to 24 hours. Press the center of each lid with a finger to ensure the lid does not move up or down. Remove the rings for storage and store in a cool, dark area.