First of all, take cleaned and cut fish pieces. Marinate the fish with lime juice and a little salt and turmeric, keep it aside for about 10-15 minutes till we are done preparing the spice mix.
Further add ginger garlic paste, chillies, mustard paste and saute it for 5-10 mins.
Now add tomatoes paste and fry for about 8-10 mins till the tomatoes are soft. After the masala starts to release oil, add salt to taste and turmeric, mix thoroughly.
Add water to prepare the gravy for the fish and let it boil for 5-7 minutes
Garnish with coriander and serve hot with basmati rice or rumali roti. Enjoy the meal !!