In a large wide pot over medium-high heat, add apples, cider, sugar, cinnamon, cloves, and salt.
Boil and stir occasionally, about 60-90 minutes. Most liquid should evaporate and apples should be very soft.
Preheat oven to 350 F.
Remove cinnamon stick.
Using a coarse mesh sieve, pass apple mixture through by pressing with a rubber spatula.
Throw away peel, seeds, and cloves.
In a baking pan, transfer apple mixture and bake.
Stir every 25-30 minutes.
Mixture will reduce by 1/2 and become dark amber and thick. About 1 1/2 - 2 hours.
Remove from oven, stir in vinegar, and cool in pan.
Can be stored for up to 1 month in the refrigerator in an airtight container.