A classic – and very easy to prepare. A fillet is the best cut of beef to use. Flank is cheaper and has equally good flavor, but it’s coarser and not quite as tender.
Cut the beef into little slivers about 1 inch long, ½ inch wide and ¼ inch thick. Brown in 2 tablespoons butter or margarine for about 5 minutes. Remove from pan and keep hot. Saute the minced onion for about 2 minutes and add to the browned meat.
Add remaining 2 tablespoons butter or margarine to the pan and saute the mushrooms. Remove the mushrooms and place with the beef. Add the flour to the pan; brown for 3 minutes. Add to the pan the stock, paprika, salt and pepper. When the sauce has thickened, add the sour cream, which should be at room temperature. Heat through gently. Pour the sauce over the meat, onions and mushrooms and sprinkle with additional paprika. Serve with noodles.