ingredients

• 1 8lb prime rib roast (I used a boneless roast) 
• 2 tablespoons black pepper 
• 2 tablespoons salt 
• 2 teaspoons chopped fresh rosemary 
• 2 tablespoons butter 
• 2 cloves minced garlic 
• 1 cup beef broth 
• 1 tablespoon balsamic vinegar beef drippings (optional) 
• 1 teaspoon salt (or to taste)

cooking

1. Preheat the oven to 450 degrees an hour before you want to start your roast. Allow your roast to come to room temperature while your oven comes to temperature. 
2. Generously cover your beef with salt, pepper, and finely chopped fresh rosemary,  Place your roast in a deep roasting pan with a rack, fat side up.  
3. Cook the roast at a higher temperature for 20 minutes.  Then reduce the oven temperature to 325 degrees. Your oven will stay at this temperature until it is done cooking. 
4. The roast will take 1- 3 ⅓ hours to reach the desired degree of doneness. 
5. For a perfect medium-rare, you want your roast to reach an internal temperature of 120 degrees (a good oven thermometer is essential here).    
6. I chose to let my roast cook until an internal temperature reaches 130 degrees.    
7. Once you remove the roast from the oven, transfer it to a carving tray or cutting board, then cover it loosely with aluminum foil (this is called tenting) and let it rest. Larger roasts need more time to rest, often up to 15–20 minutes. Once your beef has rested, slice and serve! 
8. For the au jus, place the butter and garlic in a small saucepan. Whisk in the beef broth, vinegar, and beef drippings if using. Bring the mixture to a boil, then reduce heat and simmer until slightly thickened. Season with salt to taste.
9.  Serve the au jus with the beef.