Marinate the fish with a pinch of salt and turmeric powder for 10 minutes. Heat oil in a pan and fry the fish slightly. Drain and keep aside.
Temper the same oil with nigella seeds and dry red chilli. Saute for a few seconds and then add the mango paste and turmeric powder. Saute till the oil separates.
Add the mustard paste & salt. Continue to fry again for few seconds more.
Add the water and bring it to a boil. Drop in the fried fish and green chilies. Simmer on a medium flame for 2-3 minutes.
When done, add the coriander leaves and raw mustard oil and serve with plain steamed rice.
