To prepare the coconut milk, add 1/2 cup water to the coconut and grind. Sieve and keep aside the thick coconut milk.

Add one more glass of water to the coconut residue and blend again. Sieve and keep aside the thin coconut milk.

Heat oil in a chatti (earthen pot). Splutter the mustard and fenugreek seeds.

Add the onions and chillies and saute till wilted.

Add the turmeric and red chilli powders and cook till raw smell is gone.

Add the tomatoes and cook till oil oozes out and the tomatoes are all mashed up.

Add the thin coconut milk plus more water if needed along with salt and bring to boil.

Add in the fish and cook till the fish is done.

Add the thick coconut milk, give a mix and switch off the flame. Do not boil, or else the milk will split.

Add curry leaves and keep closed till the time of serving. The more it sits, the more the flavors mingle.

Serve warm with rice or pathiris.