Saute crawfish tails in oil, stirring occasionally. Add onions and let fry 5 minutes. Add flour and mix well. Pour in tomato sauce, salt, black and red pepper. Let simmer 5 minutes. Add water and let cook about 25 minutes. Add cooked rice and stuff into hot casing. Drop in boiling water and simmer 10 minutes. Ready to eat. May be frozen before cooking. Serves 10.