Apple Ketchup

12 large, firm, tart apples, peeled, quartered and cored
1 cup (1/4 liter) sugar
1 tsp (5 ml) ground white pepper
1 tsp (5 ml) ground cloves
1 tsp (5 ml) dry mustard
2 onions, finely chopped
2 cups (1/2 liter) white vinegar
2 teaspoons (10 ml) ground cinnamon
1 tablespoon (15 ml) salt
1/2 cup (125 ml) freshly grated horseradish

Place the apples in an enameled, tinned or stainless steel pan, cover with
water, and cook slowly, without a lid, until the apples are soft and the
water has almost completely evaporated, about 30 minutes. Rub the apples
through a sieve or a food mill. Add all of the other ingredients; heat to
boiling, then reduce heat to low and simmer for an hour. Put in jars and
process or place in plastic containers with tight fitting lids and keep
refrigerated. Makes about 2 pints (1 liter).

http://www.cs.cmu.edu/~mjw/recipes/sauces/various-ketchups.html