Remove the skin and coarse parts from the kidneys. Wash in salted water. Cut into 1" squares. Pound flour into round steak and cut into pieces. Combine flour, salt and pepper. Dredge kidney in seasoned flour. Heat oil in heavy skillet and brown beef cubes on all sides, add onion and kidneys and cook slowly until brown. Cover meats with hot water, add bay leaf, parsley and celery tops. Cover tightly and simmer for 1 hour. Remove meat to deep baking dish. Add mushrooms, carrots. Mix 2 T flour with 1/2 cup water and add to pan liquor to thicken it. Pour over meat and vegetables and top with pastry crust. Bake in 350 degree F oven for about 1 hour.