Marinate Tilapia fishes with ½ tablespoon of turmeric powder and ½ tablespoon of salt. Keep them aside for 10 minutes.
Place a wok on the clay stove and pour mustard oil into it. (you can use any heating medium)
Fry both sides of the tilapia fish (no need to deep fry) and then take them out and place them on a plate.
Add black cumin seeds to the oil.
Add finely sliced onions and fry them until they turn lightly brown.
Add Kashmiri red chili powder and a little bit of turmeric powder. Sauté for a few seconds.
Add a little bit of water and stir well.
Add mustard paste and sauté for 5 minutes. Then, add water according to desired gravy consistency.
Add salt and the green chilis.
When the spicy mustard gravy comes to a boil, slide the tilapia fish one by one into the wok.
Cook for a few minutes. Add 1 tablespoon of mustard oil for flavor. Place a lid on the pan.
Remove the lid after 2 minutes.
Tilapia sorsher jhal is ready and pour onto a serving plate. If you wish, garnish it with a few green chilies. Serve it with steamed rice.