For sauce, heat butter in saucepan over medium heat until melted. Add mushrooms and garlic; cook and stir 2 to 3 minutes or until mushrooms begin to soften. Remove mushroom mixture from pan; set aside.
Combine broth, wine and cornstarch; add to same pan. Bring to a boil. Cook and stir 1 minute or until slightly thickened. Reduce heat and simmer about 10 minutes or until mixture is reduced to 1-1/2 cups. Stir in mushroom mixture, sun dried tomato spread, pepper and salt, as desired.
Meanwhile press pepper evenly onto beef steaks. Heat large nonstick skillet over medium heat until hot. Place steaks in skillet; cook 12 to 15 minutes for medium rare (145°F) to medium (160°F) doneness, turning occasionally. Remove to platter; keep warm. Add mushroom sauce to skillet; increase heat to medium-high. Cook and stir, 1 to 2 minutes or until browned bits attached to skillet are dissolved. Spoon sauce over steaks; sprinkle with thyme, if desired.