In a large skillet over medium heat, brown meat in butter. Stir in onions and mushrooms; cook for 3 minutes; remove from heat.
Sprinkle flour over meat and stir until well combined. Stir in beef broth until smooth. Cook and stir over medium heat until sauce thickens and begins to boil. Add more flour paste for added thickening if necessary.
Cover and simmer over low heat until meat is tender, about 40-50 minutes.(Do not boil.) Serve over hot egg noodled and sprinkle with fresh parsley. Yield 6-8 servings.