Fish curry (meen saaru/meen kulumbu)

I'm using merou(Dusky grouper) fillets in this recipe. Fish curry( meen saaru or kulumbu) is staple food of the coastal people( non-vegetarians) in India, may it be kerala, kolkotta, goa, Chennai, mangalore or mumbai etc. They may have different versions of it like in kerala coconut oil is used for cooking along with coconut ground paste or coconut milk etc., in kolkotta they use mustard oil in their preparations etc, in Goa they may use vinegar in their cooking( they have a lot of Portuguese influence in their cuisine) etc.. I would be adapting my version of fish curry. At home, its a big time hit always. Here goes the recipe...

Ingredients:
Fish fillets - 1 kg
onions - 2 nos
tomato - 2 nos
thick coconut milk - 1 cup
green chillies - 2 nos
ginger - garlic paste - 1 tbsp
chilly powder - 2 tbsp
coriander powder - 1 tbsp
pepper powder - 1 tsp
cumin powder - 1/2 tsp
turmeric powder - 1/4 tsp
pram stock cubes - 1 nos
Tamarind puree - 1 tsp
Gingelly oil - 4 tbsp
salt for taste
water for cooking

for seasoning:
curry leaves - 1 stalk
mustard seeds - 1/4 tsp
fenugreek seed - 1/2 tsp
gingely oil - 1 tbsp

Method:
Grind 1 onion and 2 tomatoes to a smooth paste and keep aside. In stew pot, heat oil, add Chopped onion( 1 nos) and fry till golden brown. Add ginger-garlic paste and fry.Add turmeric powder and chilly powder and fry. Now add the ground paste of onion and tomato and saute for 3 min. Add green chillies( slit lengthwise),prawn stock cubes and remaining masala powders and fry for a min. Now add fish fillets, just enough water to cover the fish, add salt for taste. cover and cook in sim for 7 min. Now add Thick coconut milk, tamarind paste and simmer for 5 min or until its done. Turn off the flame. In a tadka pan, heat oil add mustard seeds, curry leaves and fenugreek seeds. Finally do the seasoning. Serve hot with boiled rice or basmati rice.

Note:
Oil can be of your choice. Crushed aniseed may be added to the seasoning (this gives a unique aroma, and this is followed in chettinad style). Can garnish with coriander leaves also.