Take the fish in a bowl. Marinate with a little salt and ¼ tsp turmeric powder. Size the fish according to your choice.

Heat 2 tbsp. mustard oil (u can use any other cooking oil instead) in a pan and light fry the fish in low heat. Remove from pan. Keep aside. You may avoid this frying, if the fish is without scales.

Again heat 2 tbsp mustard oil in the same pan. Add kali jeera and green chili, fry in low heat for 15-20 secs. Add tomato, stir and fry for 10 to 15 secs. Add mustard paste, ginger paste, ¼ tbsp turmeric powder and salt to taste. Stir a little, say for 10 to 15 secs. Add 1 ¹/₂ cup water.

Raise heat to medium and let the water (sauce) boil. Now add the fish. Heat the fish in medium heat (say, about 5 to 7 mins) till it is well cooked. Generally, non-scaly fish take lesser time to cook. When done sprinkle chopped corriander leaf. Put lid on and remove from heat.

It is ready to serve after five minutes. Serve hot with rice.

• You may avoid ginger paste. Mustard and ginger paste together tastes different (which I don't like much, but some people do).
• You may use green tomato instead of the ripe variety to give it a sour (read, tastier) taste.
• Some people do not use kali jeera, but I do.
• In any cooking where you need to add water, it is better to add hot water. It saves time and improves the taste.