Stew the peeled and quartered apples until soft, in as little water as possible, then pass them through a sieve. To a quart of the sifted apple, add the sugar, pepper, cloves, mustard, cinnamon and chopped onions. Stir all together, adding salt and vinegar. Place on the stove and boil for approximately an hour. Bottle while hot. Seal very tight. It should be thick enough that it will just run through the mouth of the bottle.