Heat 2 tbsp oil in a deep pan. Add the onions and sautT for a while.
Add curry leaves, green chillies, ginger and garlic paste and sautT.
Then add onion paste and stir well until raw smell disappears.
Add tomato puree, chilly powder, and coriander powder adding very little water and make it a paste.
Stir for 3-4 minutes until the raw smell disappears.Add asafoetida powder and stir well.
Add 2 more cups of boiled water and little salt. Reduce heat to medium and add the fish.
Sprinkle 1/4 tsp fenugreek powder and stir. Add tomato pieces. Cook for 15 minutes.
Switch off the stove. Garnish with curry leaves. Keep this fish curry for at least 4-5 hours before serving so that the fish absorbs all the flavors. Serve with rice.