First, clean the Koi Fish really well.

Next, add 1/2 tsp Turmeric powder, salt to taste, and 1 tsp Mustard Oil to a bowl and mix it nicely. Put this paste on the fish and marinate it well.

Cover and keep the fish aside. Let it rest for around 20 minutes.

After this, make a smooth puree of the tomatoes together with ginger and 5 green chilis. Set it aside.

Now, using a sil batta or a mortal and pestle make a fine paste of the cumin seeds and coriander seeds. Do this separately. Keep them side.

When done, take a kadhai and add 4 tbsp Mustard oil.

Let the oil heat until it smokes a little. Then, gently lower the fish into the oil and fry them until golden brown on both the sides. Keep the flame on medium.

Fry them in batches.

When fried properly, take them out of the kadhai and transfer them onto a plate.

In the same kadhai add 1 tbsp of oil and let it heat.

In the oil dd kalo jeere or nigella seeds.

Stir them for a few seconds and then add the tomato ginger and green chili paste.

Sauté and let it cook. Keep the flame on low.

When the raw scent is gone, add the cumin seed paste and coriander seed paste.

Combine everything together, then add turmeric powder, Kashmiri red chili powder, and salt to taste.

Combine again and add half a cup of water.

Stir everything well and let the masala cook.

Cover and let it simmer for 5 minutes.

Stir it occasionally and let it cook until oil separates from the masala.

In the meantime, heat around 2 cups of water. Let it boil.

When the masala is cooked, add the fried koi fish to it.

Add the boiled water to the kadhai and stir everything.

When the masala comes to a simmer, add 2 tbsp of chopped coriander.

Also, add 1 tbsp mustard oil.

Keep the flame on medium and stir occasionally.

When the masala becomes semi-thick, stir it nicely and gently, keeping the flame on high.

When the masala reaches the thicker side, turn off the flame and add 1/2 tbsp Mustard oil.

Add 1 tbsp chopped coriander leaves and stir gently.

Cover the kadhai for about 5-7 minutes and let it soak all the flavors.