In a small bowl, mix together the garlic powder, onion powder, smoked paprika, salt, and pepper.
Rub the beef tenderloin with the olive oil, then rub the seasoning mixture onto the beef.
Place the beef on a roasting rack in a roasting pan and roast for 30-35 minutes, or until the internal temperature reaches 130°F (54°C) for medium-rare.
While the beef is cooking, make the horseradish sauce by mixing together the horseradish, Dijon mustard, olive oil, lemon juice, salt, and pepper.
Once the beef is cooked to your desired level of doneness, remove it from the oven and let it rest for 10-15 minutes before slicing.
Serve the sliced beef with the horseradish sauce on the side.
Notes
Tips and Tricks
Let the beef come to room temperature before cooking to ensure even cooking.Use a meat thermometer to ensure the beef is cooked to your desired level of doneness.Make the horseradish sauce ahead of time and refrigerate for a few hours to allow the flavors to blend together.Add a tablespoon of honey or maple syrup to the horseradish sauce for a touch of sweetness.