The fermented 'hilsa' nobody talks about

It’s a dark, rainy morning. The trawlers have docked after a long night of fishing. The catch is a silver, glistening beauty. There is frenzy—it’s the season’s biggest yield of ilish, the Indian herring or hilsa. Yet again, the south-west monsoon has brought good tidings to the fishing community of Chandpur, a district town on the banks of the Meghna river in Bangladesh.

Not far away, prices are soaring at an auction. The fish, fresh off the boat, will travel across borders, from India to the US and everywhere in between. But some of this catch will be cured with salt and fermented to make nona ilish. A batch will be kept for domestic consumption, and the rest exported overseas.

Curing fish and meat with salt is an ancient preservation practice. The aim is to increase the shelf life of food, for use in times of shortage. Salt acts as an agent to create a solute-rich environment, preventing fungal growth. The process also helps pack in the flavour critical to the sensory experience of the food item.

The nona ilish season coincides with the monsoon, typically August-September, when the catch is abundant. In Chandpur, the unofficial hilsa capital of the world, it is a full-fledged industry. The fish is gutted, and its scales and fins are removed. If the catch has roe, the egg sacks are taken out to be preserved separately. The fish is then cut and marinated with rock salt and turmeric as well as its own fat, extracted from the entrails. The pieces are left to cure underground in earthen jars for several months.

The fermentation process breaks down the proteins, fatty acids and lipids, resulting in a characteristic aroma. It also creates an amber gold liquid byproduct known as nonar-tel (a kind of fish oil). The glutamates or amino acids present in fatty fish such as hilsa are the source of an addictive umami flavour, possibly similar to the fish-pickling liquid, garum, known to the Romans.

Sliced nona ilish slathered in liquamen or nona-r tel (Srishti Sensarma)
Sliced nona ilish slathered in liquamen or nona-r tel (Srishti Sensarma)

Although hilsa is celebrated in, and is integral to, many of the cuisines of eastern India, mainstream conversations often leave out the salty and cured variation with an overpowering scent. Nona ilish tends to be confined to the kitchens of those who migrated from East Bengal (now Bangladesh), Bengalis who have been living in Tripura for generations, and parts of Odisha.

Sanhita Dasgupta-Sensarma, a Delhi-based corporate lawyer and food chronicler who traces her roots to East Bengal, says nona ilish may not have caught on owing to the “strong aroma, lack of exposure and blurred perception”. Attempting now to de-stigmatise such foods through pop-ups of her delivery kitchen, Gusto By Sanhita, she says fish is, in fact, preserved in many parts of the country, though many may not be familiar with the practice. In the West, it’s very different, she adds. Preserved fish has a cult following, be it Ligurian anchovies or Norwegian Rakfisk.

In Tripura, the nona ilish is known as luna. This is not a generic descriptor for salt-cured fish. “When we say luna chutney or luna-r tarkari, the fish is typically hilsa,” explains Dasgupta-Sensarma, who grew up in Agartala. Luna boasts of a robust flavour and mimics the texture and oily mouthfeel of fresh hilsa. “The umami aftertaste can last several hours post the meal,” she adds.

Due to its high salt content, the fish is soaked well in water before cooking. Patted dry, it is cut into small pieces before being stir-fried on high heat, along with onions and green chillies. The piquant scent of luna, when eaten with hot rice stained with lashings of golden mustard oil, can make for a deeply satisfying meal. It is the star ingredient in the monsoon delicacy kochu-r loti diye luna, where the root vegetable taro stolon creates an explosion of flavours.

There’s also nona ilisher bora, an heirloom recipe Dasgupta-Sensarma can’t stop talking about. The fish is stuffed in gourd leaves, usually pumpkin or ash gourd, and pleated neatly to resemble a paisley. The parcels are then gently smeared in rice-flour batter and shallow-fried. One family recipe is begun diye nona ilish: eggplants are fried until brown and tender, and added to a semi-dry fish curry prepared with onions and red chilli paste.

The preserved roe, or nona ilish-er dim, is equally prized. It can simply be cut into bite-sized chunks and stir-fried with sliced onions and green chillies. Or it can be cooked into a stew-like dish, called tawk, with tamarind. The tart curry marries the acquired salinity of the fish eggs and gives body to the dish.

“Cooking salt-cured or any kind of preserved fish can be problematic in an urban kitchen because of the pungent odour. But it can light up even the most mundane meal,” says Dasgupta-Sensarma. Like most true aficionados of cured fish, she sources it from trusted vendors back home for her weekend menus.

Odisha, which has a long coastline and large water bodies such as the Mahanadi and Chilika lake, celebrates hilsa much as Bengal does. When the monsoon catch is abundant, it’s dried and salted to be preserved for the rest of the year. Canada-based communications professional Lopamudra Mishra, who documents her Odia food heritage on the blog Away in the Kitchen, says preserved fish is associated with the “rusticity of Odia food”—she believes this is the hallmark of the cuisine.

For luni ilisha, or salted hilsa, the fish is cut lengthwise and fermented in a saturated brine for five-six months. This is followed by drying it for about a fortnight before sale. Mishra has fond memories of the luni ilisha that her mother cooked. The flavours of the dish, patrapoda, remain familiar: the cured fish coated in ground mustard, onions and tomatoes and wrapped in banana, gourd or sal leaves and toasted over a griddle. The pungency from the mustard and subtle char of the leaves balance the sharp kick of umami from the fish.

Salted hilsa is also used to make patua, with the spice-smeared fish being wrapped in banana leaves and steamed. It can be simply pan-fried, or cooked in an onion-tomato-ginger-cumin gravy to make machcha jhola. A tart curry prepared with ground mustard and chunks of sun-dried mango called ambula is also popular.

Unfortunately, the hilsa catch in the state is on the decline. “Fresh hilsa is expensive, and slowly becoming unaffordable for the marginal communities of the region. It could mean that luni ilisha is their respite,” says Mishra. New-age pop-ups are doing their bit to shine a spotlight on fermented foods—but will they succeed in bringing them into the mainstream?

Rituparna Roy is a Mumbai-based writer.