Heat a large skillet over medium-high heat and add a tablespoon of oil.
Season the beef strips with salt and pepper and sauté until browned, about 5 minutes.
Remove the beef from the skillet and set aside.
In the same skillet, add the chopped onion and garlic; sauté until fragrant.
Add the sliced mushrooms and cook until softened, about 5 minutes.
Sprinkle flour over the mushroom mixture and stir to combine.
Gradually pour in the beef broth, stirring constantly to avoid lumps.
Bring the mixture to a gentle boil and reduce heat to a simmer.
Stir in the Worcestershire sauce and sour cream, mixing until smooth.
Return the beef to the skillet and heat through, about 3-5 minutes.
Serve over cooked egg noodles.