For the Beef: One 6 1/2-pound prime rib beef roast, excess fat trimmed |
| 2 garlic cloves, peeled, thinly sliced |
| 1 tablespoon freshly ground black pepper |
| For the Red Wine-Blackberry Sauce: |
| 1/2 cup finely chopped onion |
| 3 tablespoons unsalted butter |
| 1/2 cup fresh or frozen blackberries |
| 3 tablespoons all-purpose flour |
| 1 1/2 cups canned reduced-sodium beef broth |