Elegant Prime Rib Roast 1 (5 to 6 pound) prime rib roast 2 cloves garlic Black pepper to taste Coarse salt Rub garlic, pepper and salt all over the roast. Plastic wrap and refrigerate for about 2 hours. One hour before cooking set meat on counter. Preheat oven to 325°. Insert meat thermometer into roast so that bulb is centered in thickest part, but not resting on bone or in fat. Place meat on a rack in a shallow baking pan. Do not cover or add water! Thermometer will register 135° for rare, 155° for medium and 165° for well done. Cooking time can vary, but approximately 2 ¼ hours. Let roast stand in warm place for 15 to 20 minutes before carving.