Cover the bottom of a large skillet with olive oil. Saute onion over medium heat until tender. Remove the onion and set aside.
Use a meat mallet to tenderize the steaks. Combine the flour, salt, and pepper. Dredge the tenderized steaks in the flour. Fry each side of each steak in the oil in the skillet 4 to 5 minutes over medium heat. Add more oil if needed.
Remove each steak to drain on paper towels. Add cream of mushroom soup and water to the skillet, and cook over medium heat, stirring often.
Preheat oven to 350 degrees F. Place cooked steaks in a 9 x 13 casserole dish. Cover with onions and gravy. Cover the dish with aluminum foil, and bake for 15 to 20 minutes.