Bengali fish curry in spicy mustard sauce
Soak the mustard seeds in warm water for 2 hours. If using more black mustard seeds, then remove the hull or skin of the black mustard seeds as much as possible.
Grind the mustard seeds in grinder with 2 green chilli to a slightly coarse paste. Keep it aside.
Wash and clean the fish pieces. Rub enough salt and turmeric powder and leave aside for 15 minutes.
In a kadhai or flat bottom pan, add enough mustard oil require to fry the fishes.
Once the oil is smoking hot, slightly lower the heat and slide the fish pieces carefully in to the hot oil.
Fry the fish pieces both sides till golden brown.
Slot out the fish pieces onto a plate when done.
In the same pan / kadhai add more oil if requires. Temper the oil with nigella seeds and two green chillies cut from the middle.
To the mustard paste, add the ginger paste, salt and mix it properly.
Lower the heat and add the mustard paste into the hot oil. Be careful as mustard paste will splatter. I have used the entire mustard paste, but you can always use less as per your taste and tolerance level.
Add turmeric powder and red chilli powder and saute the mustard paste on low heat till the oil starts leaving. Sauteeing the mustard paste is important step.
Once the mustard paste is thickened slightly, add sugar. Sugar is very important here because sugar brings out the real flavour of mustard.
Add around one cup of warm water and bring it to boil.
Drop the fish pieces in the gravy, and let it simmer on low heat for 6-8 minutes.
Adjust the seasonings, switch off the heat. Serve the fish in mustard gravy after 10 minutes with plain steamed rice. The fish pieces will soak some of the gravy and will enhance the taste.