- Clean the fish and marinate it with 1 tsp. turmeric powder and salt and keep aside for 15 minutes. In the skillet Heat 2 tbsp. of mustard oil in a skillet and cook the fish fillets till they are golden brown on both sides for about 2 minutes each side. Keep aside. take the oil in the same pan. Heat it and add mustard seeds and kalonji. Allow them to sputter for 30 seconds. Add in the onion paste, sliced green chillies and ginger-garlic paste and cook till everything is browned. This takes about 5-8 minutes on low heat. Add tomato paste along with spices red chilli powder, coriander powder, garam masala and salt. Cook for about 5 minutes on low flame. Add in a cup of water and the fried fish pieces. Cover and cook for about 3-4 minutes. Garnish with lemon juice, coriander leaves and serve hot with boiled rice.