1. Cook noodles according to package directions, omitting salt and fat; drain.
2. While noodles cook, heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add steak; sauté 5 minutes, browning on all sides. Remove from pan; cover.
3. Melt butter in pan over medium-high heat. Add shallots and mushrooms; sauté 4 minutes. Add garlic; sauté 30 seconds. Stir in soy sauce. Sprinkle flour over mushroom mixture; cook 1 minute, stirring constantly. Gradually add broth, stirring constantly. Add pepper, salt, and thyme sprigs. Bring to a boil; cook 2 minutes or until thickened. Return beef to pan; cook 1 minute or until thoroughly heated. Discard thyme sprigs. Garnish with thyme leaves, if desired.
Briefly cooking the gravy with thyme sprigs saves the time of stripping the tiny leaves from the stem, but still gives you the herb's woodsy flavor.