Ingredients

• 1 kg whole hilsa (ilish), scaled, cleaned and cut into 8 steaks
• 3 tbsp black mustard seeds
• 2 tbsp yellow mustard seeds
• 7 green chilies
• 1 tsp ground turmeric
• 6 tbsp mustard oil
• ½ tsp nigella seeds (kalo jeere)
• 250 ml water
• to taste salt

Method

1. 01
   Soak the mustard seeds Put the black and yellow mustard seeds in a small bowl, cover them with water, and leave them to soak for twenty minutes.
2. 02
   Marinate the fish Rub the hilsa steaks all over with half a teaspoon of turmeric and about one teaspoon of salt, and set them aside for fifteen minutes.
3. 03
   Grind the mustard paste Drain the mustard seeds and grind them on a shil pata or in a small grinder with three green chilies, a pinch of salt and two tablespoons of cold water until you have a smooth, thick paste.
4. 04
   Loosen the paste Stir the mustard paste into the two hundred and fifty millilitres of water with the remaining half teaspoon of turmeric and a little salt to make a thin, pourable sauce.
5. 05
   Heat the mustard oil Heat four tablespoons of mustard oil in a wide pan over medium high heat until it just starts to smoke, then turn the heat down to medium.
6. 06
   Temper the spices Add the nigella seeds and the four slit green chilies and let them sizzle for about ten seconds.
7. 07
   Cook the mustard sauce Pour in the mustard sauce, stir, and let it come to a gentle bubble for two minutes.
8. 08
   Simmer the fish Slide the hilsa steaks into the sauce in a single layer, spoon some sauce over them, cover the pan, and simmer on low heat for six minutes.
9. 09
   Turn and finish Carefully turn each piece of fish, drizzle the remaining two tablespoons of raw mustard oil over the top, cover again, and simmer for four more minutes until the fish is cooked through and the oil floats on the gravy.
10. 10
    Rest before serving Take the pan off the heat and leave it covered for five minutes so the fish soaks up the mustard flavour, then serve with hot steamed rice.