In a heavy bottom saucepan, saute Beef Tenderloin Tips , onions, carrot and celery in butter. Add mushrooms and cook until done. Add flour and cook until the flour taste is gone, about 5 minutes. Add beef stock and wine, a little at a time, stirring constantly. Cook until thickened, about 5 minutes. Add corn, potatoes and peas, season to taste and place in a pie pan. Cover with puff pastry and bake at 350 degrees for 2 minutes. Remove from oven and let sit 15 minutes before slicing.