In a saucepan over medium-high heat, combine the stock, wine and orange juice. Bring to a boil and add the dates and prunes. Allow fruit to partially dissolve.
Reduce heat, add mace, cinnamon, ginger, sugar and vinegar. Cook for another 5 minutes; remove from heat and allow to cool. Puree in a blender or food processor until smooth.
Pour over duck while roasting or serve on the side.
