Hilsa curry with eggplant ( বেগুন দিয়ে ইলিশ ঝোল )

 Ingredients:

Hilsa - 500 g (buy ~650 g - which should become ~500 g after cleaning)

Eggplant - 200 g (1 medium)
Potatoes - 2 medium (optional)

Green chili - 3 (slit longitudinally)

Nigella seeds - 1 teaspoonful

Turmeric powder - 1.5 teaspoonful

Red chili powder - 1 teaspoonful (or less if you want it less spicy)

Salt - according to taste

Hilsa is considered the King of Fishes in terms of taste. It takes minimal effort to cook but maximum effort to eat. Its flesh is very soft, has a lot of oil and a special strong smell which is considered so delicious that whatever way it is cooked, it tastes great. Actually, the only strong spice that goes with Hilsa is mustard, anything else will kill the special flavour of the fish itself. It is also one of the few fishes that do not always need to be fried before cooking.
But one must be very careful when eating Hilsa. It is said that every kilogram of Hilsa has 10,000 bones. The bones (especially in flesh around the spine) are vey small, so you can start chewing the fish and separate the bones in your mouth by feeling them and moving them between your teeth  slowly with your tongue. The bones in the belly meat are bigger and are better separated with fingers.

Procedure:

1. Marinate the fish with 1/2 teaspoonful of salt, 1/2 teaspoonful of turmeric, 1 teaspoonful of red chili powder for 15 minutes.
2. Chop the eggplant into ~3" long, ~1.5" wide and ~1" thick pieces. If it is a big one, first cut it crosswise into 3" long parts. Then take each part and have it lengthwise. Then make parallel 1" thick cuts lengthwise.
3. If adding potatoes, chop them into long thick pieces [ 1 crosswise cut, three parallel lengthwise cuts ( ||| ) and another two lengthwise cuts perpendicular to these three (=)] or about the same size as the eggplant.
4. Marinate the eggplant pieces with 1/2 teaspoonful of tureric powder and 1/2 teaspoonful of salt and 1 tablespoonful of oil. It tends to  absorb the oil fast. So mix these quickly (or add more oil) and evenly to give the eggplant pieces an even quote of the spices.
5. Lightly stir fry the eggplant pieces.
6. If using potatoes, lightly stir fry them too.
7. In whatever oil is left over (1 tablespoonful should be enough), add the nigella seeds as phoron. Within 10-20 seconds, add the slit green chilis. 
8. Add water after ~20-30 seconds. 
9. If you are using potatoes add them now and let cook until they are almost cooked. Then add the eggplant pieces and the marinated fish. Otherwise, add the eggplant pieces and the fish right away.
10. Cook until the fish is done (another 10 minutes in medium/low flame with cover) .
11. You may garnish it with chopped coriander leaves and serve.