Shorshe Ilish

Why does ground mustard turn bitter?

Mustard becomes bitter through two routes, and both are avoidable. The first is heat: when mustard seeds are ground for a long time in a mixer, the jar warms up and the enzyme reaction that produces the sharp, pungent compounds runs too far and tips into bitterness. Grind in short bursts with cold water instead. The second is the husk, which is bitter in itself, and straining the paste through a sieve removes most of it. Soaking the seeds beforehand in warm salted water with a green chilli is the traditional insurance against both.

Should it be black mustard or yellow?

A mixture, in roughly three parts black to one part yellow. Black, or more accurately brown, mustard carries the aggressive pungency the dish is known for, while yellow mustard is milder and slightly sweeter and rounds off the edge. All black is punishing for anyone not raised on it; all yellow tastes tame and faintly like a table condiment. The salt and green chilli ground with the seeds are not seasoning so much as part of the chemistry, and they are always added at the grinding stage.

How do you tell the fish is cooked without overcooking it?

Hilsa is thin and fatty and needs twelve to fifteen minutes at most. It is done when the flesh has turned from translucent to opaque all the way in to the central bone and comes away from it when nudged with a spoon. There should be no glassy pink anywhere near the spine. Past that point the fish goes dry and starts to shed its oil into the sauce. Because fish is a common source of foodborne illness when it is not fresh, buy hilsa with clear eyes, firm flesh and a clean smell, keep it refrigerated, and cook it the same day.

Steamed or cooked on the stove?

Steaming, the bhapa method, is gentler and gives a cleaner, more pungent sauce, because the mustard is never in direct contact with a hot pan. Stove top cooking in a covered kadai is quicker and gives a slightly cooked, mellower mustard flavour, which some households prefer. Either way the flame must stay low. Mustard paste boiled hard develops exactly the bitterness the soaking and straining were meant to prevent.

What about the bones?

Hilsa has a great many fine intramuscular bones in addition to its main frame, and this is simply part of the fish rather than a fault in the cooking. There is no preparation that dissolves them. Eat it slowly, take the belly pieces if you want the fewest bones and the most fat, and do not serve it to a small child without going through it carefully first. Anyone who wants the mustard sauce without the hazard can use it over a boneless fish, though the result is a different dish.

What can replace hilsa?

Nothing replaces it exactly, since its oiliness and particular flavour are what the mustard is built against. Bhetki, rohu and pomfret are all cooked in shorshe sauce and all work; salmon, being similarly oily, is the closest substitute outside Bengal. Cooking time changes with thickness, so a thick fillet needs a few minutes more. For other ways of cooking river and sea fish, see macher jhol and Kerala fish curry. Our note on omega 3 sources sets out how oily fish compares with capsules, and the cardiac nutrition course covers where fish sits in a heart focused diet.