Wash the fishes and cover and mix with just a pinch of turmeric powder and salt
Heat a pan with 1 teaspoon of mustard oil and fry the fish pieces
Set aside the fried fish pieces.
On a separate pan, add the rest of the mustard oil and add the black cumin, onion slices, ginger and garlic pastes and green chilli slices.
Meanwhile, on a separate bowl, add the white mustard paste, salt, turmeric powder and water. Stir and pour the mixture to the pan with the spices.
Cook until the water dries up and the oil starts to float and simmer on top. When the water dries out, add 1-1.5 cups of water.
Now add the fish pieces and sprinkle the sugar, sliced coriander leaves and whole green chilies. Put the lid on and cook until the water dries out and the oil starts to simmer on top. By now a thick gravy will form.