Cut sirloin into 1/4-inch strips. Combine 1 tablespoon flour and 1/2 teaspoon salt. Coat meat with flour mixture. Heat skillet, than add 2 tablespoons butter or margarine. When melted, add sirloin strips and brown quickly on both sides. Add mushrooms, onion, and garlic; cook 3 or 4 minutes to till onion is crisp-tender.
Remove meat and mushrooms from pan. Add 2 tablespoons butter or margarine to pan drippings; blend in 3 tablespoons flour. Add tomato paste. Stir in beef stock or consume. Cook and stir over medium-high heat till thickened and bubbly.
Return browned meat and mushrooms to skillet. Stir in sour cream and wine; cook slowly till heated through. Do not boil. Keep warm over hot water. Serve over hot buttered noodles.