1. Saute the onion, shallots, dried black currants, and crushed peppercorns in butter for 5 minutes in a medium sized saucepan or until they begin to brown.
2. Whisk in the water and duck stock and stir until all the duck stock has melted and blended into the mixture. Add the black currant reduction sauce to the pan and blend the ingredients together for 3 minutes.
3. Add the cream and simmer for 2 to 3 minutes. Allow the mixture to reduce until slightly thickened. Salt and pepper to taste and serve over grilled chicken or duck.