Barisal-Style Bhapa Ilish (Steamed Hilsa in Mustard Sauce)

Ingredients

• •Hilsa fish
• •Mustard seeds
• •Mustard oil
• •Green chilies
• •Turmeric
• •Yogurt
• •Nigella seeds

Steps

1. 1Soak black and yellow mustard seeds in warm water for about twenty minutes, then grind them with a couple of green chilies into a smooth paste, straining out any bitter husks if needed.
2. 2Whisk the mustard paste together with plain yogurt, a spoonful of pungent mustard oil, turmeric, salt, and a pinch of sugar to balance the sharpness, forming a loose, pourable sauce.
3. 3Clean thick steaks of hilsa fish, known for its rich oiliness and delicate bones, and arrange them in a single layer in a heatproof bowl or tiffin container.
4. 4Pour the mustard sauce evenly over the fish pieces, scatter a few whole slit green chilies and a pinch of nigella seeds on top, and cover the container tightly with a lid or foil.
5. 5Set the covered container inside a larger pot with a couple of inches of simmering water, cover the outer pot, and let the fish steam gently for about twenty to twenty-five minutes rather than boiling it directly.
6. 6Check that the fish is opaque and just cooked through, since hilsa's delicate flesh can dry out quickly if overcooked.
7. 7Let the dish rest for a few minutes off the heat so the mustard sauce sets slightly and the flavors settle.
8. 8Serve hot over steamed rice, spooning the fragrant mustard sauce generously over each portion.