Trim pomfrets, cut the heads and clean the insides. Make fillets and cut each fillet into four pieces. Wash thoroughly and pat dry.
Apply turmeric powder and salt and set aside for fifteen minutes. Shell, devein and wash the prawns thoroughly. Dip the tomatoes in boiling water for two to three minutes.
Peel and chop finely Heat oil in a pan over moderate heat and fry the fish pieces. Drain and set aside.
Add onion to the same oil and sauté till light brown in colour. Add green chillies, ginger, garlic and bay leaf. Stir well and sauté till a nice aroma is given out.
Add prawns and continue to sauté. When the prawns are coated with the spices, add tomatoes. Mix well.
Add vinegar, sugar and salt to taste. Add fried fish and cover the pan. Allow the curry to simmer until the prawns and fish are cooked.
Mix flour with one-fourth cup of water. Blend the mixture into the curry, stirring continually until the curry thickens sufficiently. Sprinkle coriander leaves and serve hot.