1. Wash and thoroughly dry the fish. There should not be any excess moisture on the surface of the fish.
2. Sprinkle 8 grams of salt and 3 grams of turmeric powder and toss to coat. Set this aside to marinate (in the refrigerator if it is a hot day).
3. Slice 100 grams of cleaned onions along the length. These will be used to make birista (fried onion).
4. Roughly cube 150 grams of cleaned onion and put it in the jar of a grinder.
5. Peel fresh ginger, chop roughly and add it to the same jar.
6. Grind the onion and ginger until smooth. Don't add any extra water during grinding.
7. Cube the tomatoes into small chunks.
8. Slit green chillies along the length.
9. Weigh the yoghurt, then beat with a fork until smooth.
10. Weigh out the dry spice powders in a bowl together—turmeric, cumin, red chilli, and Kashmiri red chilli.
11. Heat a kadai or a wok until very hot (250ºC). Pour all of the mustard oil (80 grams) and wait for it to start smoking. Once it smokes, lower the heat and wait for the smoke to subside and the oil to cool down a little.
12. Next, add the sliced onions from Step 3 and fry patiently until barely light brown. This should take about 6 minutes for this quantity of onions. Immediately strain and set aside. Remember, the onion will keep darkening due to residual heat even after you take it out of the oil. If it darkens too much it will turn bitter.
13. In the same oil fry the marinated fish in small batches. Fry the belly pieces (peti) separately from the back pieces (daga or gada). For a kalia, the fish should be nicely browned outside. Set the fried fish aside. We will cook the kalia in the same oil so that the sauce has the flavour of the fish.
14. Add ghee to the oil and wait for it to melt.
15. Lower the heat. Add dried red chillies, bay leaves, and whole garam moshla, i.e., cardamom, cloves and cinnamon, and finally whole cumin seeds.
16. Add the onion and ginger paste. Braise this until it darkens in colour and the moisture dries up.
17. Add the dry spice powders, stir and sprinkle a couple of tablespoons of hot water to prevent them from sticking to the pan and burning. Braise until the raw smell of the spices goes away (about 6 minutes).
18. Add the salt and the sugar.
19. Add the diced tomatoes and cook covered until softened. At any stage during the cooking add splases of hot water to prevent the spices from burning.
20. Turn up the heat, and add the beaten yoghurt stirring vigorously so that the yoghurt doesn't split.
21. When the oil (rogan) floats to the top, add the raisins and stir.
22. Once everything is well cooked, add 500 grams of boiling hot water.
23. When the sauce comes up to a boil, gently introduce the fried fish into the sauce. Also add the slit green chillies and the fried onions from Step 12.
24. Simmer the kalia until the consistency is like a sauce. A kalia should not be too thick. Plus, keep in mind that the fish will soak up a lot of the sauce and the gravy will thicken by the time you serve it.
25. Turn off the stove, sprinkle Bengali garam moshla and cover with a tight lid. Let this rest for at least half an hour before serving with plain boiled rice, or a polao.

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