Begin by peeling, coring, and chopping 4 pounds of tart apples into small pieces. In a large bowl, combine the chopped apples with 4 cups of granulated sugar and 1/2 cup of fresh lemon juice. Mix gently to ensure all pieces are coated in sugar, then cover the bowl and refrigerate for at least 4 hours or overnight.

While the apple mixture macerates, place a small plate in the freezer. Strain the macerated fruits over a bowl to separate the liquid from the apple pieces. Reserve the liquid for cooking the jam.

In a large saucepan, pour the reserved liquid from the strained apples and bring it to a boil over medium-high heat. Add the strained apple pieces back into the saucepan and stir to combine.

Allow the apple jam to cook for 20-30 minutes, monitoring closely for the mixture to thicken. Stir frequently.

Retrieve the cold plate from the freezer for gel testing. Place a spoonful of the hot apple jam onto the plate and push it with your finger. If it wrinkles and holds its shape, it’s ready for canning.

Carefully fill sterilized jars with the hot jam, leaving about 1/4 inch of headspace. Wipe the rims of the jars with a clean cloth.

Process the filled jars in a water bath canner for 10 minutes. Allow them to sit in the hot water for an additional 5 minutes before removing.

After cooling, check each seal by pressing down in the center of the lid. Store the sealed jars in a cool, dark place.