1. Wash the prunes, cover with the water and let soak 4 or 5 hours. Use a large enamel or agate kettle for this. If prunes are presoaked, omit this step.
2. Do not drain; add the oranges, and the cloves and peppercorn tied in a bag. Simmer 1 hour. Remove the bag of spice.
3. Add the sugar, vinegar, allspice and mace. Boil 5 minutes longer. Let cool.