Preheat the oven to 325 degrees F (165 degrees C). Grease a 9x13 inch baking dish.
Season the steaks on both sides with Cajun seasoning and black pepper. Place the steaks into the prepared baking dish. Pour the lemon-lime beverage over them. Combine the cream of mushroom soup and dry onion soup mix, and pour over the steaks.
Bake, uncovered, for about 1 hour, or until meat reaches desired doneness. Do not open the oven door during the first hour of cooking. Serve steaks with gravy spooned over.