Let the sugar caramelize until light brown. Deglaze with the red wine, rub the lemon and orange peel, squeeze out the juice and add everything together with the cinnamon stick and the cloves to the stock. Reduce to a third and strain to remove the spices and zest. Heat again together with the juice, add the halved and pitted plums and simmer until they start to soften after about five minutes. Remove the plums with the slotted spoon and set aside. This can prevent the shells from loosening.
Mix the cornstarch in a little cold water, first pour half of it into the no longer boiling stock and bring it to the boil again. If the liquid does not yet have the desired viscosity, repeat again with the remaining starch. Mix in the plum spirit, put the plums back into the stock and chill.