Using a saute pan, saute mushrooms and onions in butter over medium heat, stirring occasionally. Cook until onions are tender, add minced garlic and cook 1-2 minutes longer, until garlic is fragrant but not burnt.
Remove mushroom, onions, and garlic from pan.
Add beef to the same pan and sear over medium high heat until the exterior browns. Add 1 cup of beef broth and Worcestershire sauce, bring to a boil, reduce heat, and cover and simmer for 15 minutes.
Boil noodles according to package instructions while beef simmers.
Stir in remaining beef broth into flour then add to beef mixture.
Add mushroom/onion mixture back to pan and heat till boiling.
Once boiling stir in sour cream and turn off the heat once the mixture is hot enough to serve.
Serve over bed of egg noodles.