Seared Duck Breasts with Red-Wine Sauce and Candied Kumquats

Combine Beaujolais, chopped shallots, balsamic vinegar, crushed peppercorns, and crushed coriander seeds in medium saucepan. Boil until reduced to 1 1/2 cups, about 12 minutes. Add orange juice and boil 5 minutes. Add chicken broth and boil until reduced to 3 cups, about 15 minutes. Strain. Do ahead Sauce can be made 2 days ahead. Cover and chill.
Preheat oven to 250°F. Using sharp knife, score skin of duck breasts diagonally to create 3/4-inch-wide diamond pattern. Sprinkle duck with salt and pepper. Heat 1 large and 1 medium skillet over medium-high heat. Place 2 duck breasts, skin side down, in large skillet and remaining duck breast in medium skillet. Cook until skin is brown and crisp, about 8 minutes. Turn; cook until brown and thermometer inserted into center registers 130°F for medium-rare, about 6 minutes. Transfer to rimmed baking sheet and place in oven to keep warm.
Drain kumquats , reserving syrup. Pour off fat from skillets, reserving 2 tablespoons fat in large skillet for sauce. Heat large skillet with fat over medium-high heat. Add reserved sauce and 4 1/2 tablespoons reserved kumquat syrup. Boil until sauce is thickened and reduced to 3/4 cup, about 5 minutes.
Slice duck breasts crosswise into 1/2-inch-thick slices. Divide duck breast slices among 6 plates. Drizzle duck with red wine sauce, garnish with candied kumquats, sprinkle with crushed peppercorns, and serve.