Cut the cat fish into 1 inch thick cylindrical discs and remove the intestines. Place in bowl and pour very hot water on the fish. This process of pouring hot water on the fish toughens the skin of the fish so that the pieces do not disintegrate while cooking the soup. Leave for about two minutes and wash the fish with cold water. You should also wash off any slimy substance on the outer skin of the fish at this time.Boil the a few cubes of raw white yam. When soft, pound with a mortar and pestel till a smooth paste is formed, then set aside. You can substitute white yam with yam powder or potato puree for the thickening.Wash and pound/ blend the Utazi leaves, and Chilli pepper and the Cray fish and set aside. Utazi is bitter in taste and only used for flavoring so one or two leaves should be enough especially when using the fresh leaves. Place the cat fish in a pot and pour enough water to cover the fish. Add the seasoning and cook till done. Feel free to add beef and dry fish to this soup recipe.When the cat fish is almost done add the crayfish, pepper and Utazi leaves blend. Also add the yam paste in Small lumps and salt to taste.Note: Catfish is what makes Nsala soup what it is, giving it the unique taste that it has so therefore it is very essential to this recipe. The only other fish that can replace the Catfish is the Conger Eel. Nsala soup or White soup is a tasty, fast and easy recipe that has its origin in the riverine areas of Nigeria. Nsala soup is perfect for a cold rainy day due to its spicy taste. Because it is so easy to prepare, you can count on it to save the day when you run out on a few days before the big soup day.