In a pan add the fish pieces, salt, turmeric powder. Boil and cook them in water as needed. Cool this to room temperature and drain the liquid and break them into small pieces. while breaking down if you find bones remove them. NOTE: add little water as needed if you added excess water you can make a soup from it.
To the fish add onion, chili powder, salt as needed (note we already cooked fish with salt), black pepper powder, cumin powder, green chili, crushed garlic cloves and mix well.
In a pan heat oil. add cumin seeds, curry leaves. once the curry leaves stop splattering add the fish and sauté until the oil starts to separate and serve. NOTE: while sautéing in middle add oil if needed.