Canning method
Wash half-pint or pint canning jars. Because the process is only 5 minutes at 0–1,000 feet, sterilize the jars and keep them hot until filling. Prepare two-piece lids according to the manufacturer directions. Preheat the boiling-water canner.
Select about one-fourth underripe and three-fourths fully ripe tart apples. Sort and wash them. Remove the stem and blossom ends, but do not peel or core the apples. Cut them into small pieces.
Place about 3 pounds of prepared apples and 3 cups water in a covered pot. Bring to a boil over high heat, reduce the heat, and simmer for 20 to 25 minutes, or until the apples are soft. Extract the juice through a damp jelly bag. Do not squeeze the bag if you want clear jelly.
Measure 4 cups apple juice into a large kettle. Add the optional strained lemon juice and 3 cups sugar; stir well. Boil rapidly over high heat until the mixture reaches 8°F above the local boiling point of water, or until it sheets from a spoon. Remove from the heat and quickly skim off the foam.
Immediately pour the hot jelly into hot, sterile half-pint or pint jars, leaving 1/4-inch headspace. Wipe each rim with a dampened clean paper towel and apply the two-piece lids.
Process half-pint or pint jars in a boiling-water canner for 5 minutes at 0–1,000 feet, 10 minutes at 1,001–6,000 feet, or 15 minutes above 6,000 feet. Begin timing when the water returns to a full boil.
After processing, turn off the heat, remove the canner lid, and wait 5 minutes before removing the jars. Cool upright and undisturbed for 12 to 24 hours. Check the seals, remove the screw bands, label, and store. Refrigerate any unsealed jar and use promptly.