Marinate the fish heads with ¼ tbsp of salt and ½ tsp of turmeric powder. Keep them aside for about 10 minutes.

Heat the wok (Kadai) on a medium to high flame and add 3 tbsp of mustard oil to it.

Fry the marinated fish heads in the hot mustard oil. (Pro tip: Fry the hilsa heads patiently until golden. Turning them too early can cause them to break).

Take them out on a plate when fried nicely on both sides.

Fry the potato cubes in the same oil until slightly brown in the edges. Add ¼ tbsp of salt & ¼ tsp of turmeric into it.

Take out the shallow-fried potatoes on the same plate with fish heads.

Add the remaining 1 tbsp of mustard oil in the kadai.

Strain water from the marinated ash gourd. Add it to the oil. Add the black cumin. Give it a good stir.

Add the ginger-garlic paste into it.

Stir for 2 minutes to fry well until the raw smell is gone.

Add all the remaining spices.

Stir fry everything very well. (Pro tip: Cook the spices until their raw smell fades away. This will give the dish a deeper flavor.)

Add ¼ cup of water into it.

Again, add ¼ tbsp of salt into it.

Add the fried fish heads & potatoes to it. Mix well.

Add 1 cup of water.

Add the green chilies.

Cover the pan with a lid. Let the hilsa head with ash gourd boil on medium heat.

After about 7 to 8 minutes, check if water has dried and whether the ash gourd has softened.

Sprinkle the roasted masala and mix well.

Break the fish heads into 2-3 pieces and mix well with the dish.

Pour Hilsa head with ash gourd on a plate to serve.