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Fish Sauce – All You Need to Know | Instacart’s Guide to Groceries

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Last Updated: May 2, 2022

What is fish sauce?

Fish sauce is a condiment of Southeast Asian descent made from fish packed in salt and fermented for a long time. The sauce itself has an intensely pungent aroma of fish, while the flavor is more complex. Fish sauce is a mix of salty and sweet, making it the perfect way to add umami to a dish.

Fish sauce, known as nam pla in Thailand and nuoc mam in Vietnam, can’t be left out of Thai dishes like Pad Thai or som tum or Vietnamese dishes like larb or nuoc mam cham. You’ll definitely notice a difference in flavor if you do forget it!

What is the origin of fish sauce?

While fish sauce is most popular in Asia, its origin dates back to Greek and Roman times. Back then it was known as garum and produced in factories in Northern Africa, Portugal, and Spain as far back as 400BC. Garum was likely traded along the Silk Road where it eventually made it to India and then to current day Vietnam, which was then the Champa Kingdom. 

The Vietnamese learned the present-day fish sauce brewing technique from the Chams. The oldest standing fish sauce producer in Vietnam is Lien Thanh, who still produces to this day. 

How is fish sauce made?

While Thai and Vietnamese fish sauces may have a similar flavor, they vary in their creation. Thai fish sauce primarily uses anchovies, but it can include carp, herring, mackerel, or sardines, depending on the brand. Vietnamese fish sauce, on the other hand, almost always uses a species of anchovy called ca com, which lives off the coast of the island of Phu Quoc in the southwestern region.

The process of making fish sauce begins with purchasing the fish. Some smaller fish sauce makers will travel to the market themselves to pick out the fish they want, while bigger producers have their own expert buyers. They are looking for fish that are clean, fresh, and of similar size. It takes 30-40t of fish to produce a 10,000L batch of sauce. 

Once the fish are ready to go, they get placed in a vat and mixed with salt to start the fermentation process. The most commonly used fermentation vats hold roughly 10,000kg of fish and 15kg of salt. The fish get stirred every day until they break down into a smooth paste. This stage takes about 6 months to complete.

The fish paste goes into cloth-lined baskets, which allows the liquid to slowly extract itself from the paste by gravity. Once all of the liquid is out of the paste, the extracted fluids go in shallow ceramic bowls that are then set out in the sun. The sun causes the excess water to evaporate from the fish sauce, concentrating it even further. Depending on the weather, it can take a week up to a month. 

Finally, they transfer the fish sauce from the bowls to large ceramic urns, where it continues to age anywhere from another month to a few years. The longer the aging process, the sweeter and less salty it becomes.

What should I look for when buying fish sauce?

There are a few things to look for when deciding which fish sauce to buy. 

  • Origin: The country of origin tells you what kind of flavor to expect from the fish sauce. Thai fish sauce has a heavier, saltier flavor, while Vietnamese fish sauce is lighter and sweeter.
  • Nitrogen Levels: In some brands of fish sauce, there will be a number, like 40°N, that indicates the level of nitrogen per liter of fish sauce. The higher the number, the higher the quality.
  • Additives: Fish sauce in its purest form should only contain salt and fish. There are brands that add additives like sugar or hydrolyzed wheat protein which can change the flavor or affect those on a gluten-free diet.

If you are looking to have your groceries delivered, you can easily shop for fish sauce via Instacart. After adding a product to your cart, use the “Instructions” option to notify your Instacart shopper about any preferences or specific directions on how to choose the best products. Shop for fish sauce.

How to store fish sauce

Store fish sauce in your pantry for up to a year past the best-by date if it isn’t unopened. The best-by date is usually 3-4 years after it bottling. Once you open the fish sauce, store it in the fridge in between uses. Due to its high salt content and no perishable ingredients, the sauce should remain in great quality for at least a year. If you decide to store an open bottle in your pantry, place it in a cool, dark place, and it will last for a few months.

How to tell if fish sauce is bad

Just in case you don’t finish your bottle of fish sauce by the best-by date, the first thing you can do to see if it is starting to go bad is to smell it. If it has a rotten odor, it is time to toss it. You can also try tasting a small amount to see if it still has the original fresh flavor. If you come across any mold forming in the bottle, that is also a sign it needs to go.

Darkening of color, increasing cloudiness, and salt crystals forming are signs of the sauce aging, but they don’t affect the taste. 

What can I substitute for fish sauce?

If you don’t have any fish sauce on hand or don’t prefer to use it due to a vegan diet, you have many options. Soy sauce, tamari, and coconut aminos are great vegan substitutes that don’t sacrifice the flavor. Worcestershire and oyster sauces are both made by fermenting fish but do have different flavors or seasonings added to them. 

How to find fish sauce

Fish sauce is a critical component of a wide variety of dishes in Southeast Asian countries. While each country has its own style and brands, you can try them all on Instacart. Simply add them to your cart and choose from either same day or future delivery at checkout. 

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