Apply salt and turmeric powder on the fish and set aside for half an hour. Then shallow fry to a light golden color. Grind the nuts, chillies, coconut, poppy-seeds, onion and garlic to a paste. Heat the ghee and fry the paste, adding a little milk now and then till the ghee floats to the top. Now add the tomatoes and all the spices and curd and cook till dry. Add the fish and thin coconut milk and cook for 10 minutes. Now pour in the thick coconut milk, heat to simmering and remove from fire. Serve hot, garnished with coriander leaves and fried cashew nuts.