Combine rosemary, gingerroot, salt, and pepper; rub on all surfaces of meat. Place roast, rib side down, in shallow roasting pan. Insert meat thermometer. Make sure that the themometer bulb doesn't rest on bone.
Roast in a 350 degree F oven until meat themometer reaches desired temperature. Allow 2-1/2 to 2-3/4 hours for 140 to 145 degrees (medium-rare); 3 to 3-1/4 hours for 155 degrees (medium); and 3-1/4 to 3-1/2 hours for 170 degrees (well done). Cover meat; let stand about 15 minutes before carving. Serve with Onion Gravy. Makes 10 to 12 servings.
Cook 1 large onion, chopped, in 3 tablespoons fat from pan drippings, margarine, or butter in a medium saucepan until tender but not brown. Stir in 1/4 cup all-purpose flour, 1/4 teaspoon salt, 1/8 teaspoon pepper, and 1/8 teaspoon dried rosemary,crushed. Add beef broth to any pan drippings to equal 2 cups. Stir into flour mixture. Cook and stir over medium heat until mixture is thickened and bubbly. Cook and stir 1 minute more. Makes 2-1/2 cups.