1) Clean and cut the fish.
2) Marinate them in chilly powder, turmeric powder and salt for 1/2 hr.
3) Shallow fry the marinated fish pieces and keep them aside.
4) Roast and grind cinnamon, cloves, cardamom and cumin.
5) Grind together roasted spices, mustard seeds and half the sliced onions.
6) Heat oil.
7) Add the remaining sliced onions, garlic, ground spices and a pinch of turmeric powder and fry well.
8) Add sliced tomatoes, tomato ketchup, salt and saute till they are cooked.
9) Add well beaten curd and 1 cup water and simmer for 10 - 15 minutes.
10) Add fried fish pieces and continue simmering for another 10 minutes.
11) Garnish with chopped coriander leaves and serve.