Prepare steak by washing and drying the pieces and pounding with a metal meat hammer on both sides. Put in a bowl, cover with the buttermilk and soak overnight in refrigerator. Discard the buttermilk.
In shallow bowl, create a dredge of the flour, salt and pepper. Heat oil in large deep skillet with a lid. Coat each steak well in the dredge and brown on both sides of the hot oil.
When browned, remove the steaks and pour the dredging flour into the skillet and brown the flour like a gravy roux. When flour is browned, stir in the water briskly, blending out the lumps. Return steak to skillet, cover with onion slices and bring the liquid to a boil. Reduce heat, cover and simmer for 20 to 30 minutes or til onions and meat are tender. If gravy appears too thick, just stir in more water. Serves 4 to 6