Beef Stroganoff

Slice meat thin, about 2"x 2" (partially freeze the meat first). Heat 1 tablespoon of butter and 1/2 tablespoon oil in a large frying pan. Saute the mushrooms over medium heat for about 3 minutes. Add the onions and/or shallots, saute 2 minutes more. Remove from skillet and set aside. Heat remaining butter and oil, until it bubbles, then add the meat and brown. Remove the browned meat from the pan. Put the flour in the pan and mix in with the oil in the pan until well blended. Gradually add the sherry and the beef broth whisking until mixture is smooth. Cook over high heat and turn to medium-high and reduce by half. Add meat and season (to taste) and add the mushrooms/onions. Cook over medium-low heat about 5 minutes, stirring frequently. Just before serving stir in sour cream but do not allow to come to a boil. Serve over noodles.