Soak the mustard in 1/2 cup water for an hour. Then grind along with chilies, pinch of salt, pinch of turmeric powder and some water into a fine paste. Keep aside.
Apply lime juice over the fish and keep aside for 10 minutes. Rinse well. Mix the fish pieces with the mustard paste and rest of the ingredients.
Transfer it to a steel tiffin box. Put the lid on. In a pressure cooker add some water and then place a stand. Now place the steel container over it and steam for 12-15 minutes. (Do not keep the vent).
Garnish with coriander leaves and few chilies. Serve it with hot steamed rice.
