Combine 3 teaspoons thyme, salt, and pepper; rub evenly over tenderloin. Cover and chill 2 hours.
Combine 2 teaspoons thyme, mushrooms, wine, broth, and garlic in a large saucepan, and bring to a boil. Reduce heat, and simmer until reduced to 1 1/2 cups (about 1 hour).
Combine water and cornstarch, and stir into wine mixture. Bring to a boil, and cook 1 minute, stirring constantly.
Remove wine mixture from heat; set aside, and keep warm.
Preheat oven to 40
Heat oil in a large nonstick skillet over medium-high heat.
Add tenderloin, browning on all sides, about 12 minutes.
Place tenderloin on a broiler pan coated with cooking spray. Insert meat thermometer into thickest portion of tenderloin.
Bake at 400 for 20 minutes or until thermometer registers 145 (medium-rare) to 160 (medium).
Place tenderloin on a serving platter, and cover with foil.