Cut 1 lb of beef sirloin into 1/4 inch strips. Combine 1 Tbsp flour and 1/2 tsp salt. Coat meat with flour mixture. Heat skillet, then add 2 Tbsp butter. When melted, add sirloin strips and brown on both sides. Add one 3oz can of sliced mushrooms (drained). [Fresh sauteed mushrooms are even better!] Add 1/2 c chopped onion and 1 clove minced garlic. Cook 3-4 minutes until onion is tender.
Remove meat and mushrooms from pan. Add 2 Tbsp butter to drippings. When melted, blend in 3 Tbsp flour. Add 1 Tbsp tomato paste (or catsup). Stir in 1-10 oz can of condensed beef broth. Cook and stir over medium high heat until thickened and bubbly.
Return browned meat and mushrooms to skillet. Stir in 1 c sour cream and 2 Tbsp dry white wine. Cook slowly until heated through. Do not boil. Serve over noodles or rice.