Wash and clean fish. Coat with salt and ½ tsp turmeric and keep aside.
Soak tamarind and take out pulp.
Make a paste of white mustard seeds with 1 green chili and a pinch of salt.
Heat 6 tbsp of oil in a saucepan and lightly fry the fish, and remove to a plate.
In the same oil in the saucepan, temper with kalojeera; add the white mustard seed paste, put 1 tsp turmeric, 1 tsp chili powder, 2 whole green chilies and salt. Keep stirring. Add 1 cup water, mix well and let it come to a boil. This is the gravy or the ‘Ganga’ side.
When the gravy thickens, place the fish carefully in it and cook for 2-3 minutes. Keep aside.
In a separate pan, make the ‘Jamuna’ gravy by adding 2 tbsp oil. Temper it with the dark mustard, tamarind pulp, ½ tsp chili powder, 2 whole green chilies, sugar and salt.
When the gravy thickens, take the fish and place the flip side in it. The top side will have the ‘Ganga’ gravy, while the bottom side will have the ‘Jamuna’ gravy.
Cook for 2-3 minutes. Pour 1 tbsp fresh mustard oil on top and serve with hot rice.
