1. Preheat oven to 350°.
2. Combine thyme, garlic, salt, and pepper; coat beef tenderloin with mixture. Heat a large ovenproof skillet coated with cooking spray over medium-high heat. Add beef; cook 2 minutes on 1 side until browned. Turn beef over.
3. Transfer skillet to oven; bake at 350° for 20-25 minutes or until internal temperature reaches 125°. Transfer beef to a carving board; tent with foil, and let stand 10 minutes (internal temperature will rise to 130° for medium-rare).
4. Cut beef crosswise into 8 slices; transfer to serving plates.