Sterilize 7 quart-sized canning jars, lids, and rings by boiling them in a large canning pot for 10 minutes. Keep them warm until ready to use.

Peel, core, and slice the apples into thin, even pieces to ensure even cooking and packing. Place the sliced apples in a bowl of cold water mixed with ¼ cup of lemon juice to prevent browning while you prepare the syrup.

In a large pot, combine water, sugar, ClearJel, cinnamon, nutmeg, and salt. Stir continuously over medium heat until the mixture thickens and begins to bubble. Once thickened, add the apple cider vinegar or lemon juice, stirring constantly, and allow it to boil for 1 additional minute.

Drain the apples and carefully fold them into the hot syrup. Stir gently to ensure all slices are evenly coated without breaking them.

Using a slotted spoon, pack the apple slices into the sterilized jars, leaving 1 inch of headspace at the top. Then, ladle the hot syrup over the apples, ensuring they are completely covered while maintaining the 1-inch headspace. Remove any air bubbles by gently running a non-metallic spatula along the inside of the jar.

Wipe the rims of the jars with a clean, damp cloth to remove any residue. Place the sterilized lids on top and screw on the rings until fingertip tight—firm, but not overly tightened.

Place the jars in a water bath canner, ensuring they are fully submerged under at least 2 inches of water. Bring the water to a rolling boil and process the jars for 25 minutes (adjusting for altitude if necessary).

After processing, carefully remove the jars and place them on a towel-lined counter to cool for 12-24 hours. Do not disturb them during this time. You should hear the "pop" of the lids sealing.

Once cooled, check each lid by pressing down on the center. If it does not pop back, the jar is sealed correctly. Store in a cool, dark place for up to 12 months.