Cut beef across grain into about 1 1/2×1/2-inch strips.
Cook mushrooms, onions and garlic in butter in 10-inch skillet over medium heat, stirring occasionally, until onions are tender; remove from skillet.
Cook beef in same skillet until brown. Stir in 1 cup of the broth, the salt and Worcestershire sauce. Heat to boiling; reduce heat. Cover and simmer 15 minutes.
Stir remaining 1/2 cup broth into flour; stir into beef mixture. Add onion mixture; heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in sour cream; heat until hot (do not boil). Serve over noodles.