The mushroom sauce is a great low-carb sauce because it's not thickened with flour or cornstarch. This is a wine- and broth-based sauce, and the flavors are concentrated as the mixture is reduced.
10 ounce shiitake mushrooms
4 (4-ounce) beef tenderloin steaks, trimmed
1/2 teaspoon pepper
1/4 teaspoon salt
1 teaspoon olive oil
1/4 cup minced shallots
1/2 cup Marsala wine
3/4 cup beef broth
1/2 teaspoon Dijon mustard
1 tablespoon light butter
How to Make It
Remove and discard stems from mushrooms; slice mushrooms.
Sprinkle steaks with pepper and salt; coat with cooking spray. Place a large nonstick skillet over high heat. Add steaks; cook 3 to 4 minutes on each side or until desired degree of doneness. Place steaks on a platter; keep warm.
Heat oil in pan over medium heat until hot; add shallots, and sauté 1 minute. Add sliced mushrooms; sauté 4 minutes or until tender. Add wine; bring to a boil, reduce heat, and simmer 2 minutes.
Add broth and Dijon mustard; boil 5 minutes or until liquid is reduced by half. Remove from heat. Add butter; stir until butter melts. Spoon sauce over steaks.