Remove your roast from the fridge. Let it sit on the counter for 1 to 2 hours to come to room temperature. This ensures even cooking.
Preheat oven to 500 degrees.
In a small bowl, combine horseradish, garlic cloves, salt, pepper, and olive oil. Spread over the entire roast.
Place the roast into a roasting pan, fat side up. Roast at 500 degrees for 15 minutes. Reduce the heat to 325 degrees and continue roasting for until the internal temperature of the roast reaches 120 degrees. You should plan on 15 minutes per pound, but actual cooking time depends on a variety of factors. Always use a meat thermometer to ensure accurate results.
Remove the roast from the oven when it reaches an internal temperature of 120 degrees. Allow the roast to rest in the roasting pan for 20 minutes. As it sits the internal temperature will rise to 130 degrees (medium rare). Slice against the grain into slices for serving.
Serve with additional prepared horseradish or creamy horseradish sauce.
Creamy Horseradish Sauce
Stir all ingredients together in a medium sized bowl, including a dash or 2 of Tobasco or Worcestershire sauce if desired. Salt and pepper to taste.