Marinate the cleaned fish pieces with turmeric powder, chilli powder, pepper powder, vinegar and salt. Keep it aside for 10 minutes. Shallow fry the marinated fish pieces, it should be half cooked only. Make sure that fish pieces do not become brown colour.
In the same pan, splutter cardamom, cinnamon & cloves. Add ginger, garlic, onion & green chili. Saute till the onion becomes soft. Add tomato and pepper powder and cook till it becomes soft. Add medium thick coconut milk and salt. When it boils add the fried fish pieces. Cover and cook in low - medium flame for 5-10 minutes. Add cashew paste to the thick coconut milk and stir well. Add the thick coconut milk to the curry. Cook for 5 minutes (approx). When it is about to boil, remove from gas. Garnish with coriander leaves.
Serve it with appam, bread, chappathi etc;