Ilish Macher Paturi (Hilsa Paturi, Ilish Paturi)

At first, clean and pat dry the banana leaves for making small parcels. You can either sun dry them or heat them over a pan.
Make a fine paste of black mustard seeds, grated coconut, salt, and green chilis. It is better to use both black and white mustard seeds in equal proportions.
Take the mustard paste in a separate bowl and then add turmeric powder, Kashmiri red chili powder, and mustard oil and salt to taste. Mix well.
Marinate the hilsa fish pieces by coating with the spices mix. Keep them aside for 10 minutes.
Place each piece of fish on a separate banana leaf and add little bit of mustard oil, one green chili, and one red chili on it. Repeat the same process for the other pieces of fish.
Wrap the fish pieces with the banana leaf, ensuring that it is fully covered. Use a cotton string to tie the parcel firmly.
Preheat a tawa on the gas stove and heat mustard oil.
When the oil is hot, place all the banana leaf wraps side by side on the tawa and cover it with the lid.
Once one side is cooked, flip the banana leaf wraps and cook the other side.
Steam the banana leaf wraps for 5 minutes on each side. You can place a lid on the pan.
Ilish Paturi is ready and now unwrap the banana leaf and serve it with steamed rice.