4 pounds boneless duck breast halves with skin (about 4)
1 teaspoon salt
1/2 teaspoon pepper
1/2 cup finely chopped shallots or onions
2 garlic cloves, chopped
2 tablespoons sugar
1/3 cup raspberry vinegar
1 cup chicken or vegetable broth mixed with 1 tablespoon cornstarch
2 cups raspberries (12 ounces), divided
1 1/2 tablespoons unsalted butter, cut into bits
Put a large shallow roasting pan in middle of oven and preheat to 400. Pat duck dry and trim off any excess fat. Score skin in a crosshatch pattern at 1/2-inch intervals with a sharp knife, then season with salt and pepper. Roast, skin side down, in hot pan until an instant-read thermometer inserted diagonally into center registers 125, 20 to 25 minutes.
Turn on broiler. Turn duck skin side up. Broil 4 to 6 inches from heat until golden brown, about 2 minutes. Transfer duck to a cutting board and let rest (skin side up) 10 minutes.
While duck rests, pour off all but 1 tablespoon fat from pan, and then add shallots and garlic and sauee over medium heat until golden brown, about 2 minutes. Add sugar and cook, stirring, until dissolved. Stir in vinegar, scraping up brown bits. Add broth mixed with corn starch, stir to combine and bring to a simmer. Stir in half of raspberries. Force sauce through a fine-mesh sieve into a small saucepan, discarding solids. Skim off excess fat. Over low heat, swirl in butter. Remove from heat and add remaining raspberries. Slice duck and serve with sauce. Serves 6 to 8