An old favorite from my childhood. Found this in my recipe folder on a yellowed piece of scrap paper, in Mom's handwriting, spattered with what I really hope was gravy ;-D
1 pound beef round steak
1 3-oz can (approx 2/3 C) sliced mushrooms with their liquid
2/3 C water
1 envelope beefy-onion dry soup mix
1 C dairy sour cream
2 Tbsp all-purpose flour
6 C cooked egg noodles
Trim fat from beef; reserve. Slice beef diagonally across the grain into very thin strips. Heat a large skillet and render the fat from the beef trimmings; remove trimmings leaving melted fat in skillet. Add enough butter to the beef fat in the skillet to make 3 Tbsp. Add the sliced beef and brown.
Stir in mushrooms with their liquid, water, and soup mix, bring to boil. Meanwhile, blend together sour cream and flour. Reduce heat under skillet to low simmer, and gently stir in the sour cream mixture. Simmer gently, stirring constantly, until sauce is smooth and slightly thickened- it will still be runny. Serve hot over cooked egg noodles.
Omit flour and serve over cooked shredded spaghetti squash. Sauce will be runnier, but it's still yummy!