First, make a mustard paste. You can use a grinder or a "Silnora/Shilbatta." Add 2 green chilies and 1 teaspoon of salt to the mustard as you grind it into a paste, then set it aside.

Next, prepare the fish. If the fish are large, cut them in half. If they are small, you can use them whole. Make sure the fish are cleaned well. Rub the fish pieces with ½ teaspoon of salt, ½ teaspoon of turmeric powder, ½ teaspoon of red chili powder, and ½ tablespoon of mustard oil. Let them sit for 10 minutes.

Heat some oil in a pan and fry the fish pieces.

In a deep pan (a Karai is ideal), heat 5 tablespoons of mustard oil until the oil's color changes. Sprinkle in ½ teaspoon each of turmeric powder, salt, and red chili powder.

Add nigella seeds (Kalojire/Kalonji) to the oil to temper it. Then, add the onion paste and fry until the onion changes color. Add tomato paste, ginger, and garlic paste. Cook over medium heat until the oil separates from the mixture.

Now, add the mustard paste, curd, turmeric powder, slit green chilies, and red chili powder. Cook over medium heat for 2 minutes.

Finally, add water and bring the mixture to a boil.

Gently pour the mixture in and let it cook on low heat for at least 5 minutes, making sure to cover the pan with a lid.

Your Pabda Macher Tel Jhal is now ready! Serve it with warm, steamed rice.