1. Clean and cut the fish in ¾-inch slices, reserving the heads and bones.
  2. Sprinkle the slices with lemon juice and dust with flour, salt and pepper.
  3. Fry in olive oil until tender.
  4. Make a fish stock by cooking the heads and bones in the water with the onion, parsley, celery and bay leaf.
  5. Simmer for ½ hour.
  6. Strain the stock and remove any edible fish particles from the heads.
  7. Add these to the stock with the fried fish and ñame.
  8. Cook slowly until the ñame is tender.
  9. Correct the seasoning.
  10. A little aji chombo may be added for a "hotter" soup.