Duck
On hot grill sear the duck breasts rare, about 3 minutes each side. Sprinkle with salt and pepper. Let rest 5 minutes.
Polenta
Bring water to a boil with salt in a 4-quart heavy pot, then add polenta in a thin stream, whisking. Cook over moderate heat, whisking, 2 minutes. Reduce heat to low and simmer polenta, covered, stirring for 1 minute after every 10 minutes of cooking, 45 minutes total. Remove from heat stir in butter, parmesan and saffron to taste.
Orange Currant Sauce
Combine all ingredients in a heavy sauce pan. Boil on medium until reduced to 1-½ cups. Puree in a food processor and pour through a screen, discard solids. Stir in butter, serve warm over duck and polenta