Partially freeze steak; trim fat from steak. Slice steak diagonally across grain into 2- x 1/4-inch strips.
Cook steak in 2 tablespoons hot oil in a large skillet over medium heat until browned. Remove steak from skillet; set aside, and keep warm.
Saute mushrooms, peppers, and shallots in margarine in skillet over medium-high heat until tender. Remove from heat. Add brandy, and immediately ignite with a long match. Let flames die down.
Combine sour cream and next 3 ingredients; add to vegetable mixture. Cook over medium-low heat 8 minutes, stirring frequently. Stir in steak, and cook until thoroughly heated. To serve, spoon steak mixture over noodles.