Bengali fish and mustard oil

Almost every Bengali recipe begins the same way: heat the mustard oil until it smokes, then take it off the heat and let it come down. No other Indian cuisine does this as a default. Punjabi cooking uses ghee or refined oil at temperature; Tamil cooking uses coconut oil or sesame oil; neither is taken to the point of visible smoke before anything goes in. That single step is the most reliable fingerprint of the cuisine, and it is not a matter of taste. It is a matter of chemistry.

The oil is the cuisine

Mustard oil pressed from Brassica juncea is roughly forty to forty-five per cent erucic acid, a long-chain monounsaturated fat, and it carries glucosinolates — the same family of compounds that makes mustard sharp. When crushed seed meets water, an enzyme called myrosinase converts those glucosinolates into allyl isothiocyanate, which is the compound that stings the nose. In raw oil it is present and aggressive.

Heat drives it off. Taken to the smoking point, around 250 °C for refined oil and lower for cold-pressed, the volatile fraction flashes away and what remains is a nutty, mild fat with a very high smoke point and a faintly bitter back note. This is why the step exists: the raw oil would ruin a delicate fish, and the smoked oil will not. The procedure looks like a ritual; it is a deodorisation.

It also has a political dimension worth knowing. Because of the erucic acid content, mustard oil has been restricted as a food in parts of North America and Europe for decades, and in the United States it is commonly sold labelled "for external use only". Bengalis have been cooking in it for centuries and regard the restriction as an outsider's misunderstanding — which, given the difference between older cold-pressed oil and modern low-erucic cultivars, is not entirely unfair.

Fish is the geography

The Bengal delta is the largest river delta on earth, and its cooking is organised around what the rivers deliver. Fish are classified not just by species but by habitat — river, pond, brackish, sea — and by an inherited humoral scheme of "warm" and "cold" properties that decides what a sick person, a nursing mother or a growing child should eat. That scheme is not scientific, but it is a coherent system for making decisions, and it is still in daily use.

Hilsa, ilish, is the fish the cuisine is built around and the national fish of Bangladesh. It is anadromous: it lives in the Bay of Bengal and swims upriver to spawn with the monsoon, and it is exceptionally oily for a river fish. That oil is why it is cooked with mustard paste — the fat and the pungency cut each other, and the dish, shorshe ilish, is essentially an emulsion of fish oil, mustard and green chilli. It is also full of fine bones, which is why the cuisine has an elaborate grammar of cutting and an equally elaborate etiquette for dealing with bones in the mouth.

Five courses, and what they are for

A formal Bengali meal is served in sequence, not all at once, and the sequence is fixed enough to have names. It opens with something bitter — shukto, usually built on bitter gourd or neem leaves, sometimes with a little fish head. Then dal. Then the fish or the main vegetable course, which may be several dishes. Then a sweet-sour chutney. Then mishti, the sweet.

The stated reason is physiological: bitters stimulate appetite and are held to be good for the liver; the chutney clears the palate; the sweet closes the meal. The unstated reason is rank. The fish course is the expensive course, and the number of fish dishes at a wedding announces the family's standing as clearly as the guest list. A meal that begins with bitter greens and ends with sweetened milk is a meal that has been designed to be read.

The everyday version strips this down. Lunch on a weekday is rice, dal, one vegetable, maybe a fish, and a piece of something sour — no shukto, no mishti. The elaborate order survives in the ceremony and in the restaurant, which is the usual pattern: the ritual preserves what the household has already dropped.

1947 divided the kitchen

Partition split the delta, and with it the cuisine. East Bengal — Bangladesh — kept the great rivers, the hilsa run and the majority of the fish; West Bengal kept Calcutta, the bhadralok food culture and the restaurants. The two are often described as one cuisine divided by a border. That is not quite right. They diverged, and the divergence follows water more than religion.

Calcutta's food was itself a nineteenth-century construction. The city's Bengali middle class developed a kitchen that borrowed heavily — from the British (baked goods, the "cutlet", the "chop"), from Odia cooks who worked in Bengali households, from Mughal-derived dishes that arrived with the Nawabi court, and from the Chinese community in the city. The result was a cuisine more cosmopolitan and more mutton-heavy than the delta's, and it is the one most outsiders think of as "Bengali food".

East Bengal's cooking retained a rougher, more riverine character: more fish, more dried fish, more mustard, less dairy, less beef and mutton. When partition moved millions of people west, it moved that cooking into Calcutta, and the city absorbed it in layers that are still legible in the street food — the refugee-settlement snacks, the fried fish stalls, the sweets that changed recipe depending on which district the shop's founder came from.

What outsiders miss

Three things, and each of them changes the food. The first is the fish head. Muri ghonto, a dish of rice cooked with fish head, is a delicacy and a mark of hospitality; serving it to a guest is a compliment. The second is dried fish, shutki, which has an aroma that is genuinely difficult for a newcomer and is used as a seasoning rather than a protein. The third is the bitterness at the start — a cuisine that opens with bitter greens is doing something no other Indian regional kitchen does as a matter of course, and it is the clearest surviving trace of an older, medical idea of what a meal is for.

And one warning. Mustard oil that has not been smoked tastes raw, sharp and slightly acrid, and it will dominate everything. If a restaurant's Bengali fish tastes of mustard in the way a mustard sandwich tastes of mustard, the kitchen did not heat the oil. That is the tell, and it is more reliable than any judgment about the spicing.

How to eat it

Start with the bitter dish, take a small amount, and do not skip it — the rest of the meal is calibrated against it. Eat the fish with rice, not with bread, and use the rice to mop the mustard gravy. Leave the bones on the edge of the plate; there will be many. Finish with a spoon of chutney and then, if it is offered, the sweet, which in a Bengali household is not dessert but the closing bracket of the meal.

Then notice what has happened to your sense of what "Indian food" means. There is no cumin-forward gravy here, no cream, no tandoor. There is a thin mustard emulsion, a bitter opening, a fish with too many bones and a sweet at the end. This is not a variation on a national cuisine. It is a different cuisine that happens to share a passport.

This is entry 06 of Food in About India. The pillar's argument — grain and fat, not spice blends — is set out on the pillar page.