Dress up simple, yet elegant, beef tenderloin with a homemade horseradish sauce for a delicious dinner that's perfect for a crowd.
Preheat oven to 400°.
Trim fat from tenderloin; fold under 3 inches of small end. Rub the tenderloin with oil. Combine the breadcrumbs, parsley, pepper, and 1/2 teaspoon salt. Rub the tenderloin with crumb mixture; coat with cooking spray. Place tenderloin on the rack of a broiler pan or roasting pan. Insert a meat thermometer into thickest portion of tenderloin. Bake at 400° for 30 minutes. Increase oven temperature to 425° (do not remove roast from oven). Bake an additional 10 minutes or until the thermometer registers 140° (medium-rare) to 155° (medium). Place the tenderloin on a platter, and cover with foil. Let stand 10 minutes for tenderloin to reabsorb juices. (Temperature of roast will increase 5° upon standing.)
Combine 1/4 teaspoon salt, the sour cream, and the remaining ingredients in a small bowl. Serve with the beef.