- 2 1/2 cups fresh orange juice
- 1/4 cup fresh lime juice
- 3 tablespoons maple syrup (preferably dark amber or Grade B)
- 1 tablespoon finely chopped canned chipotle chiles in adobo
- 1 (3- to 4-inch) cinnamon stick
- 2 whole cloves
- 1 teaspoon salt
- 3 (1-lb) boneless Muscovy duck breasts with skin or 6 (7- to 8-oz) Long Island (also called Pekin) duck breast halves with skin
- 1 1/2 teaspoons salt
- 1/2 teaspoon black pepper
- Special equipment: an instant-read thermometer
- Boil all sauce ingredients in a 2- to 3-quart heavy saucepan over moderate heat, skimming foam occasionally, until syrupy and reduced to about 1 cup, 30 to 40 minutes. Let stand while duck broils.
- Remove rack of a broiler pan, then add 1 cup water to broiler pan and replace rack. Preheat broiler with pan 5 to 6 inches from heat.
- Pat duck breasts dry and score skin at 1-inch intervals with a sharp knife (do not cut into meat), then sprinkle all over with salt and pepper. Broil duck breasts, skin sides down, 4 minutes for Long Island duck or 8 minutes for Muscovy, then turn over and broil until thermometer inserted horizontally into center of a breast registers 130°F (see cooks' note, below), 8 to 10 minutes more for medium-rare. Transfer to a cutting board and let stand 5 minutes. Add any juices accumulated on cutting board to sauce and simmer until slightly thickened, 1 to 2 minutes.
- Holding a sharp knife at a 45-degree angle, cut each duck breast into thin slices and serve with sauce.