Rub the fish with the marination ingredients and set aside for 10 minutes. Heat oil and fry till both sides are golden brown, not necessary to cook them fully. Drain and set aside.
In a saucepan, heat oil. Add in the onion and saute till soft. Add the ginger garlic paste, chilli and tomato and cook till tomato is soft.
Add the powders and stock cube and saute for a minute. Drain the tamarind off the liquid. Add the liquid, tomato paste and loomi. Add 1 cup of water and salt and allow the mixture to simmer for around 10 minutes.
Add in the coriander leaves and fish and cook till the fish is done.
Serve hot with steamed rice.