Heat oil in a pan & splutter mustard seeds & fenugreek. Saute crushed ginger & garlic. Add curry leaves also.
Make a paste with chilli, coriander & turmeric powder & add it.Grind the coconut with 3-4 small onion & little water.Add ground coconut when oil starts appearing. Mix well & stir for 3-4 minutes.
Add cocum,salt& fish. Pour required water & cook. Once the fish is done add oil & take off from gas. Garnish with curry leaves.