Skip the hassle of carving a bone-in roast with this mouthwatering boneless prime rib.
- 6 pounds boneless beef prime rib roast (trimmed and tied)
- black pepper
- 2 tablespoons dijon mustard
- 2 teaspoons prepared horseradish
- 1 teaspoon garlic powder
- 1 teaspoon dried thyme
- 1/2 teaspoon dried rosemary
- 1/2 teaspoon onion powder
- Line a roasting pan with heavy-duty aluminum foil and position a roasting rack inside of it.
- Transfer the prime rib fat side up to the middle of the roasting rack. Tent the prime rib loosely with foil, and allow it to stand at room temperature for 1-2 hours.
- Preheat the oven to 500° F.
- Place the Dijon mustard, horseradish, garlic powder, thyme, rosemary, and onion powder into a small bowl. Stir to combine.
- Using the back of a spoon, spread the mustard mixture over the top surface of the meat.
- Transfer the roasting pan to the middle rack of the oven.
- Roast the prime rib for 20 minutes.
- Reduce the oven temperature to 325° F. Continue roasting the prime rib for 75-100 minutes longer, or until the meat reaches an internal temperature of 120-125° F.
- Remove the roasting pan from the oven.
- Allow the prime rib to rest on the rack for 15 minutes.
- Transfer the prime rib to a cutting board. Carve and serve immediately.