(CNN) — Fish sauce — nước mắm, or literally “salted fish water” — is a Vietnamese culinary icon, a must-have national ingredient up there with olive oil or soy sauce.
But it’s fair to say the production process isn’t the most flavorful, thanks to the pungent funk emanating from anchovies fermented in giant wooden vats for a year.
They’ve been in business since 1950 and pride themselves on their reputation as one of the leading producers on an island that many Vietnamese believe is responsible for the country’s finest fish sauce.
On the hunt for umami
The extensive repertoire of beautifully prepared Vietnamese dishes they serve, such as seafood and grapefruit salad or lobster with stir-fried vegetables, is largely underpinned by the unique flavor profile and the standout umami – the “fifth taste” or the unique flavor offered by Phu Quoc fish sauce.
But you don’t have to look far for the taste of Vietnamese fish sauce. It’s found in pho, spring rolls, com tam, banh xeo, com thit nuong, and dozens of other ubiquitous dishes.
A Phung Hung employee guides visitors through the factory.
How the magic happens
The main ingredients in fish sauce are cá cơm (black anchovies) and smaller white anchovies. Together they make up about 95% of the fish used. Bigger fish like sardines and herring make up the rest.
Traditionally, fish were caught in the Andaman Sea around Phu Quoc, but today they tend to come from Tho Cho Island, about 70 miles away. They are only caught between April and September, which largely corresponds to the rainy season.
Phung Hung have their own fishing boats which allow them to oversee the entire production process. When the fish are caught, they are immediately dumped while still on the boat, then salted and stored so that the fermentation process has already begun, using fresh catch whenever possible.
They use salt sourced from the southern coastal province of Ba Ria-Vung Tau and add it in a one part to four part fish ratio.
When the fishing boats land, Phung Hung staff collect the 200-kilogram containers of fish and blend them in their own barrels.
Fish sauce barrels used to be handcrafted from wood boi loi, a tree from the Phú Quốc National Park, which is now so threatened with extinction that wood has to be imported from Cambodia. Some have compared the importance of wood to wine aging in oak casks, giving it its own unique flavor profiles.
The strong barrels consist of 54 wooden slats that are tied together by hand with rattan cord. It takes two men three weeks to make one.
Once the barrel is filled, workers climb up the outside, don white rubber boots, and begin compacting and crushing by stepping on the mixture.
After that, every day for a whole year, the liquid that oozes from the fish is drained and then returned to the tank – but, crucially, no stirring or mixing is required like there is in the production of fish sauce in other provinces Vietnam’s is the case.
Workers monitor the contents and taste the sauce to decide when a batch is ready.
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Part of the sauce’s secret is Phú Quốc’s unique combination of environmental factors, including the right humidity and heat, which allows the mixture to slowly reduce to leave between three and four thousand liters of fish sauce per barrel.
The final stage comes when they send a sample of the sauce to the lab for an intensity grade, measured in nitrogen, a byproduct of the fermentation process. Without the correct level, it cannot be certified on the bottle label.
The mildest variant starts at 35° N, the most intense at about 45° N.
Phú Quoc fish sauces – there are more than 70 different manufacturers on the island – tend to have higher nitrogen levels, resulting in complex and varied flavor profiles.
The first press
If you’re looking for the most valuable and expensive fish sauce, it’s poured undiluted and unmixed straight from the first press of a single vat.
Look for the words “nước mắm nhi” on the label. That is, it comes from the first liquid withdrawal of the cask. Some call it “extra-virgin fish sauce.”
“Fish sauce is the national soul, the national essence of the Vietnamese people, which sets the country’s cuisine apart from the rest of the world,” says Anon. “With every Vietnamese meal, pride of place is given to a small bowl, a sauce that ties everything on the table together.”
He explains that here are several layers to taste.
“It would be too easy to say that fish sauce tastes fishy or even salty. Quality blends have a salty, well-rounded taste that you can even taste straight from the bottle. Your thoughts might go to the taste of fresh fish or sitting on the beach.
“Fish sauce sometimes has a hint of sweetness, a mineral taste, or a hint of caramel.”
“This is killer.”