- Combine the first 5 ingredients in a small bowl.
- Preheat the oven to 450˚F. Place the prime rib, bone-side down, in a roasting pan. Brush horseradish mixture on the top and sides of the roast.
- Roast the beef 20 minutes, and then reduce oven temperature to 325˚F. Finish cooking roast to desired doneness, allowing about 20 to 25 minutes per pound for rare to medium rare. To gauge doneness, always use an instant-read meat thermometer, inserted into the centre of the thickest part of the roast. For a rare roast, remove from the oven when the internal temperature is 120°F to 125°F; 130°F for medium rare; and 140°F for medium.
- When beef is cooked, transfer to a plate, loosely cover with foil and rest 10 to 15 minutes before thinly slicing.
Option: To make jus to serve with the roast, remove fat from cooking pan, pour in 3 cups of beef stock (or broth), simmer 5 minutes, pour into a sauce boat and serve with the beef.
Note: Total time and cooking time will be determined by your desired doneness for the meat.
Recipe Options: Try the horseradish crust on another type of beef roast, such as top sirloin or top round. Use chopped rosemary in the crust instead of thyme. Serve Yorkshire pudding with the beef by making the ones featured in this website recipe: Herb-Rubbed Roast Beef with Yorkshire Pudding.