Take a pan. Heat coconut oil and add shallots, fennel seeds and curry leaves. Saute well. Add the grated coconut and green chillies.
Saute continuously until it turns deep brown (it should not be burned). Now add all the masalas and take it off the heat. Let the mixture cool for sometime.
Grind the mixture till paste. Keep it aside.
A shallow clay dish called Chatti or Manchatti is used to prepare this dish. But if not available, take a wide bottomed pan and heat oil.
Splutter mustard seeds and curry leaves. Add ginger pieces and fry for sometime.
Add some water, ground paste and put kudampulli into it. Bring it to boil. Lower the heat and add the fish pieces.
Close the lid and simmer for 10 mins until fish is cooked. Adjust salt and serve with steamed rice.