In a large mixing bowl, combine 4 lbs of diced tart apples, 4 cups of granulated sugar, and ½ cup of lemon juice. Stir gently and refrigerate for at least 4 hours or overnight.

While the apples macerate, place a small plate in the freezer for the gel test. Gather equipment including a large pot, wooden spoon, and sterilized jars.

After resting, strain the macerated apples, reserving the liquid. Bring the liquid to a boil in a pot, add the strained apple pieces, and cook for 20-30 minutes.

To test the texture, drop a spoonful of jam onto the frozen plate. If it wrinkles when pushed, it’s ready; if not, cook longer.

Carefully fill sterilized jars with hot jam, leaving ¼-inch headspace. Wipe the rims clean and process in a boiling water bath for 10 minutes.

Remove jars from water bath and let cool completely. Check seals before storing.