Doi Machh (Fish in tangy yogurt gravy)

This dish is a very light Bengali gravy. Till a few months back I didn't get it right (the yogurt would curdle sometimes) till my friend pointed out the trick was to turn the heat off when you added the yogurt and them simmer. The boro elach (big black cardamom) is a must, as it adds its characteristic smoky flavor to it.

Ingredients (serves 6):
6 medium sized pieces of fish, preferably Rohu (Any other carp will do)
2” stick of cinnamon
2 cloves
2 green cardamoms
1 big black cardamom
100 gms yogurt
½ tbsp turmeric
1 tbsp chilli powder
½ tbsp cumin powder
½ tbsp coriander powder
2 split green chillies
2” piece of ginger
2 medium sized onions
1 bay leaf
6 tbsp mustard oil
Fresh coriander to garnish
Salt and sugar to taste

Method:
Make a paste with the onion and ginger and keep aside.
Whisk the yogurt with salt, sugar, chilli, turmeric, coriander and cumin powders and keep aside.
Rub the fish with a little salt and turmeric and fry them in hot oil. Keep aside. In the same oil, lightly fry the bay leaf, cinnamon, cardamom, cloves, then add the ginger-onion paste. Fry till the oil separates, now release the fish and fry some more. Turn off the heat completely and add the whisked yogurt to this. Carefully fold in the yogurt then turn the heat on and simmer. Cover to cook for 5 minutes. Garnish with the split green chillies and coriander and serve.