Thyme richly accents the flavor of beef tenderloin steaks and transforms steak and portobello mushrooms into an elegant entrée all in one skillet.
Mix stock, wine, thyme, garlic powder and pepper in medium bowl until well blended. Add mushrooms; toss to coat well
Melt butter in large nonstick skillet on medium-high heat. Add steaks; cook 8 to 10 minutes or until desired doneness, turning once. Remove steaks from skillet; keep warm. Add onion to skillet; cook and stir 2 minutes or until softened. Add flour and salt; cook 1 minute, stirring constantly
Pour mushroom mixture into skillet. Boil 10 to 12 minutes or until sauce is thickened and mushrooms are tender, stirring occasionally. Add steaks to sauce; heat 1 minute. Serve immediately