First make a paste by grinding ginger, red chillis, and one onion. Pour the paste in a large bowl and add with it yoghurt, sugar ,salt and fish and keep for 30 minutes.
Heat the oil in a wok , add bay leaves, cardamoms, cloves and cinnamon and fry for few seconds. Add the remaining onions and fry till onions turn golden brown. Then add fish paste ,stir and cover the pan on low heat till fish is cooked. Adjust the consistency as desired.