Grind together the onion, ginger, and garlic. Now put the paste on a sieve, and squeeze out all the juice.

The fish pieces should be about 5-6 inches long. Marinate with turmeric powder and salt.

Heat the oil in a wok, and add the fish pieces. Fry till both the sides turn golden brown in colour. Remove from wok. Keep aside.

Now pour out some of the oil from the wok. Turn flame to low.

To the remaining oil, add the fenugreek seeds. Wait for the seeds to turn brown. Remove and discard.

Bring the flame to medium. Now pour in the onion-ginger-garlic juice. Let this boil for 1 min.

Add salt, and a pinch of turmeric powder. Stir.

Turn off the flame. Then add in 4 heaped tbsp of curd. Mix well.

Now simmer this for 2 mins.

Finally add in 1 tbsp of sugar. Mix well.

Now slowly place the fried fish pieces into the gravy.

Add in the ghee, and the slit green chillies. Cover and cook for 4-5 mins

The gravy should be slightly sweet. So add in the remaining 1/2 tbsp of sugar if required. Adjust salt.

Serve with rice.

PS: If you add the curd on the flame, it may split.