Sauté vegetables: Heat butter and oil in a Dutch oven or heavy bottom skillet over high heat. As soon as it is melted and hot, add the mushrooms and onions. Stir, and allow to cook until liquid has evaporated and they are barely golden brown. Add garlic and onion dip mix, stir, and allow to cook for another 1-2 minutes. Remove from heat and set aside.
Sear and braise meat: Using the same skillet over high heat, cook the meat until brown. This should only take a few minutes. Add one cup of the beef broth and the Worcestershire sauce, reduce heat to low, cover, and simmer for 15 minutes.
Cook the noodles: Bring a large pot of salted water to a boil. Add the egg noodles and cook until they are al dente. Drain and keep warm.
Make the gravy: Whisk flour with the remaining cup of beef broth until smooth. Pour into pot with beef and stir well. Add the mushroom mixture back in with the beef and heat just until it starts to boil over high heat, stirring constantly. Allow the mixture to cook at a gentle simmer for about a minute.
Stir in sour cream: Reduce the heat to low and stir in the sour cream. Heat the mixture until everything is heated through. Do not allow the cream to boil. Serve over noodles.