Wild Plum Ketchup

10 lb (4 1/2 kg) plums, stemmed (about 7 1/2 quarts)
10 cups (2 1/2 liters) sugar
1 quart (1 liter) white vinegar
1 teaspoon (5 ml) ground cinnamon
1/2 teaspoon (2 ml) grated nutmeg
1/2 teaspoon (2 ml) ground cloves

Add the sugar to the plums, and place them in an enameled or stainless-steel
pan over medium heat. Cover. After 30 minutes, increase the heat and stir
the plum-sugar mixture. Break some of the plums with a wooden spoon.

Continue cooking, stirring the mixture occasionally, so that it does not
stick to the pan. In 15 minutes, all of the plums should be cooked through
and mashed. Remove from heat and cool.

Mash the mixture with a wooden spoon. Put the mashed pulp through a fine
sieve, and continue mashing until all of the liquid and some of the pulp
go through. Discard the pits and the skins. There should be about 4
quarts of liquid. Boil the vinegar together with the spices for a few
minutes. Add the vinegar-spice mixture to the plum liquid, then boil
vigorously, stirring constantly, for 15 minutes, or until the liquid has
reduced to 4 quarts again. Pour into bottles or jars. Process.
Makes 8 pints (4 liters).