Slice beef thinly
Season with salt and pepper
Heat oil or butter in a pan
Brown the beef quickly
Remove the beef from the pan
Sauté chopped onions
Add sliced mushrooms
Cook until softened
Add minced garlic
Sprinkle in flour
Stir to coat the vegetables
Pour in beef broth
Add Worcestershire sauce
Simmer until slightly thickened
Stir in sour cream
Return the beef to the pan
Heat gently without boiling
Serve over egg noodles, rice, or mashed potatoes
Garnish with parsley if desired