1) Coarsely pound (chathakkuka) the pearl onions, ginger & green chillies. 2) Put the above onion, ginger, green chilli mix into a pan along with the raw mangoes and 2 tbsp of coconut oil. 3) Add chilli powder, turmeric powder, salt and 1 cups of water and cook until mangoes are half done. 4) Now add the fish pieces and adjust salt and water and cook the fish covered, on low flame. 5) When the fish is almost done, add tamarind water and adjust spices and salt and cook till fish is done. 6) At this point, add coconut milk and bring to a boil and turn off the stove. 7) Now, it is time to season. For this, fry the sliced onions and curry leaves in coconut oil until onions turn brown and crispy. 8) Pour the seasoning on to the curry. :- Serve hot with Rice, Idiappam, pathiri etc.