What exactly is fish sauce?


Fish sauce is not something you just put on fish

Fish sauce is an essential ingredient in countless Asian recipes, from curries to soups to sauces and beyond.  It packs a fishy odor, and a strong salty and umami flavor punch, so you don’t need to use much.

It’s low calorie, but also high sodium, and while we were reviewing Thai food last week, the sodium content of Thai recipes made with fish sauce looked high.  But we spend so much time and energy obsessing about salt in our food, forgetting that thousands of years ago people had exactly the opposite problem: salt was scarce.  People settled close to sources of salt, and salt production and trade were lucrative businesses.  Anything that could add salt to food was welcome and valuable.

I first read about the origin of fish sauce in the book Salt – A World History.  Fish sauce dates back to the Roman Empire, when salt was scarce and a prized commodity.  The original version was made by fermenting fish, or just fish guts, with salt.  For months!  Which sounds pretty disgusting.  How did that combination even happen?  And who thought it was  good idea to let fish guts and salt sit around for months and then eat it?  But they did, and not just in ancient Rome.  According to the author of “Salt-A World History”, people in South East Asia independently invented fish sauce.   Great minds thinking alike, without the benefit of the internet or Pinterest.

Fish sauce has disappeared from Italian cuisine, but remains a dominant force in Asia.  These days it’s made primarily from anchovies fermented with salt, although some less expensive brands are made with anchovy extract, salt and other flavorings like sugar.  Because of its strong unique flavor, it takes some getting used to.  But once you do, most traditional recipes don’t taste right without it.  And because it adds sodium, you don’t need to add extra salt to those recipes.

So exactly how much sodium does it have?  According to the USDA nutrient database, “fish sauce” has 1413 mg sodium per tablespoon.  That’s a lot, I thought. So I did an experiment.  I dissolved 1/2 tsp of salt in 1 TB of water.  1/2 tsp is slightly less than 1413 mg of sodium, but the resulting tablespoon of salt water was extremely salty.  Unpleasantly so.  A taste of fish sauce, by comparison, was definitely not as salty.  Fish sauce nutrition labels have values roughly in that range.  Red Boat sodium is a little higher, but taste testers like its more complex flavor, due to higher protein content.

I have a Thai cookbook that gives ranges for fish sauce in the recipes, typically 1 to 3 or 4 TB for a recipe that may serve 4-6 people.  If 4 people split 1 TB of fish sauce, that’s about 350 mg/serving, not terrible compared to some fast food.  And keep in mind that in some recipes, it’s used in a dressing or sauce, some of which collects on the plate and is not actually eaten.  So plan accordingly if you’re concerned about sodium.  If you’re making your own Asian recipes, use the minimum of fish sauce, or cut back on other salty ingredients like soy sauce.

Certain foods benefit from the flavor of fish sauce.  Tofu, rice, noodles and vegetables come to mind.  Which brings up a conundrum.  What do vegetarians and vegans do about fish sauce? It is after all made from fish.  And it is a great way to flavor meatless dishes.  There are a number of recipes online for non-fish fish sauce (an oxymoron by the way. Just call it something else please!).  The point being you have to make your own.  Most involve some combination of sugar, soy sauce, garlic, mushrooms and other seasonings. Unfortunately without the actual fish it isn’t going to taste the same, but it might be a nice flavor on its own.  Some of the recipes sound a bit like traditional Vietnamese nuoc cham, minus the fish sauce.  Oh well.

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