Wash the fish well, cut into halves, rub salt and turmeric powder into it. set aside for 10 minutes. Cut potatoes into medium sized cubes, salt them and set aside.
Cut onion and garlic. Heat 1 table spoon oil and fry the diced onion, ginger and garlic for 2-3 minutes. Grind it in the mixer with one tomato and 2 green chilies
Add 3 tablespoon oil to skillet, heat well. Add fish, cover and fry well. Take fish out and set aside.
Put cinnamon, cardamom, and cloves into oil. Add the onion mixture. Keep stirring the mixture till it is dry. Add rest of the turmeric powder, coriander powder, cumin powder and red chilli powder. Add salt to taste and sugar. Keep stirring. Add two table spoons of water. Keep stirring for 2 minutes. Add 1/2 cup water and let the gravy come to a boil. Put the fried potatoes. Cover and cook on low flame. Add fish after 4-5 minutes and cook till the fish is done. Garnish with fresh coriander leaf and serve with rice or pulao.