Wash all the fish pieces properly. Add a tbsp of turmeric powder and salt,mic it all over the fish pieces. keep it for 10 minutes.
Take a small bowl. Add the mustard powder, 2 tbsp of mustard oil, curd ,1/2tsp of turmeric powder,red chilli powder, water,salt . Mix all the ingredients gently to make a thick paste.
Apply the paste all over the pieces and marinate it for 30 min
Heat 2 tbsp of mustard oil in a frying pan. Add green chilli and mustard seeds. Once it splutters ,stir for a minute
Now add the marinated fish pieces. Cover it and cook in a medium flame for 20 min till the pieces are steamed well.
Add water if require to make a smoothy mustard gravy.
When the cooking is over spread 1tbsp of mustard oil on all over the pieces and serve hot with steamed rice