Bring a large pot of salted water to a boil and cook the egg noodles according to package directions until al dente. Drain and set aside.

Melt the butter in a large skillet over medium heat. Add the sliced beef and cook until browned on all sides. Remove the beef and set it aside.

Add the diced onion, sliced mushrooms, and minced garlic to the same skillet. Cook until the onion softens and the mushrooms release their liquid.

Sprinkle the flour over the vegetables and stir for one minute to coat everything evenly.

Slowly pour in the beef broth while stirring to avoid lumps. Simmer the mixture until it thickens into a sauce.

Reduce the heat to low and stir in the sour cream. Return the beef to the skillet, season with salt and pepper, and heat through gently without letting the sauce boil.

Spoon the beef and sauce over the cooked egg noodles. Sprinkle with fresh parsley before serving.