Phan Thiet's Fish Sauce factory (Photo: Internet)

France has its wine and cheese, Italy its olive oil and balsamic vinegar and Spain its ham, but the one product that defines Vietnam's diverse cuisine is by far the smelliest: sauce made from festering fish.

Nuoc mam, or fish sauce, is a fixture at almost every Vietnamese meal and the pride of the province of Binh Thuan, one of the country's leading sources of fish sauce and where around 600 factories of varying size produce 36 million litres a year.

The distinct, and pungent, substance can be used as a marinade, a stock base, a flavour enhancer or diluted to create a dipping sauce, and is a major industry in the beach towns of Phan Thiet and Mui Ne, where its production is taken as seriously as vinters take their winemaking.

And like wine, the quality ranges from simple kitchen standard to high-end connoisseur specialities, depending on when in the fermentation process the liquid is drawn off.

Prices, however, do not vary much, starting at about 10,000 dong ($0.56) and going up to 20,000 dong. But competition between producers is fierce, with the Sao Vang Dat Viet, or Gold Star, award given to the finest product.

While there is no official tour of the factories, the first stop for curious gourmands is often Phan Thiet's Fish Sauce Joint Stock Company (FISACO), the biggest operation of all, producing 16 million litres of nuoc mam under four brand names a year.

The company gives a somewhat smellier take on a wine tasting tour, offering a guided walk through the processing compound and the opportunity to sample some of the end products. A stomach strong enough to tolerate the stench is an advantage.

"Anchovies or salmon are best, but you can use pretty much any fish. We collect ours from the port or market as soon as the fishermen dock every morning," said company guide Van Nhi, as he meandered between jars and barrels.

NO WASHING FIRST

The factory makes the fish sauce in two ways: the traditional method of covering fresh fish with salt and then placing it in earthen jars that are then left out in the sun to basically rot for up to three months.

And then there's the quicker option of replacing the jars with huge, cylindrical wooden tanks, where the liquid that comes out is placed back into the mixture at regular intervals, and then the first sauce is ready to be decanted five days later.

"We don't wash the fish first. They have already been washed by the sea," Van added.

Reports emerge periodically of nuoc mam workers dying from suffocation after falling into vats of fish sauce in the making, or trying to rescue comrades who have fallen in.

At FISACO, visitors can try a selection of sauces, much like at a wine-tasting, and also purchase bottles. Some brands are even packaged and promote like wines, with labels proclaiming a "pure and well-balanced flavour".

But for a more rustic experience, visit almost any house in Phan Thiet and Mui Ne, where yards are more often than not filled with brown earthen jars containing the olfactory-challenging fish mixture and where the air seems to shimmer more from the stench than the midday heat.

"It's very important to keep the temperature constantly high for the first few months," explained Nhu Nguyen, whose family runs a small fish sauce factory in Mui Ne.

"A higher temperature means better fish sauce. Then after a few months, you draw it off and filter it."

Once the first, high-grade sauce has been decanted, manufacturers will add more salt and water to produce a lower grade product, but like olive oil, the first collection is the best quality, and this "black gold" earns around $2 a litre.

And the taste? Despite the noxious aromas that accompany production, the nose of higher-grade fish sauces is rich, acrid, meaty and reminiscent of Worcestershire sauce.

On the palate, the caramel liquid is salty, with well-rounded salmon tones that developed quickly on the tongue. And even undiluted, it was flavoursome and appetising.

($1 = 17,825 dong)

Miral Fahmy and John Ruwitch (Copy Reuters Life!)