Pantry & Shopping
Soy, fish sauce and miso are salt that has been somewhere
These are not simply salty liquids. Fermentation has broken proteins down into compounds that add savoury depth no amount of plain salt can produce.
There is a short answer about fermented seasonings and a useful one, and they are not the same. What follows is the useful one.
The short version
- Fermentation breaks proteins into amino acids that taste savoury rather than merely salty.
- These products are salty, so they replace some of the salt rather than adding to it.
- Heat changes them, so when they go into the pan matters.
What fermentation has done to them
Each of these begins with a protein-rich ingredient that is broken down over time by microorganisms and enzymes. That breakdown produces free amino acids, which the palate registers as a rounded savoury depth quite distinct from saltiness.
Salt is present throughout the process because it controls which organisms can survive, which is why the results are all salty. The consequence for cooking is that adding one of these is adding two things at once, and only one of them is seasoning. A dish that tastes thin despite adequate salt is often missing this savoury component rather than needing more of the same.
They are salt, so budget for it
A tablespoon of any of these carries a meaningful amount of salt, and adding it after seasoning the dish will overshoot. The correct order is to add the fermented seasoning first, taste, and then decide whether any plain salt is required at all. Reduction concentrates them alongside everything else, so a sauce built on soy and then reduced hard can become aggressive.
Salt content varies substantially between brands and between types within a category, which the label will usually tell you. Lower-salt versions exist and behave differently in cooking, since some of what made the original work has been reduced with it.
Heat changes each of them
Soy sauce added to a hot pan browns and develops roasted notes, which is a different flavour to the same soy stirred in cold. Prolonged boiling drives off some of the aromatic compounds, leaving something flatter and saltier than you started with.
Miso is generally added at the end and not boiled, since heat damages both its aroma and the living cultures in unpasteurised versions. Fish sauce mellows considerably with cooking, which is why a dish can carry far more of it than the smell of the bottle suggests. Knowing which of yours tolerates heat and which does not determines where in the method each one belongs.
Using them outside their usual cuisines
A small amount of fish sauce in a tomato sauce or a stew adds depth that most people cannot identify as fish sauce at all. Soy in a beef braise or a mushroom dish reinforces the savoury character that is already there rather than importing a new flavour.
Miso whisked into a dressing or stirred into a soup base works the same way and brings a slight sweetness with it. The quantity for this use is much smaller than a recipe from the original cuisine would call for, since the aim is reinforcement.
Overdoing it makes the dish taste of the bottle, which is the failure mode that puts people off trying it again.
Other things in the same family
Anchovies dissolve into a pan and do almost exactly the same job, which is why they appear in so many sauces that taste nothing of fish. Hard aged cheeses, dried mushrooms, cured meats and tomato paste all contribute savoury depth by a related mechanism.
Combining two or three of them tends to produce more than any one of them alone, which is why classic recipes so often stack them. None of these is a substitute for salt, and a dish still needs seasoning on its own terms after they have gone in. Recognising this whole group as one category makes it much easier to work out why a dish tastes incomplete.
Buying and keeping them
These are concentrated seasonings used in small amounts, so a small bottle finished quickly beats a large one that ages. Most keep for a long time but lose aroma once opened, and refrigeration slows that for the more delicate ones.
The instructions on the container are specific to that product and are more reliable than any general rule about the category. Quality differences are noticeable, particularly in products where the fermentation was long, and are usually reflected in the price. One of each is enough to change how a great many ordinary dishes taste, which makes them among the best value on any shelf.
The takeaway
Add the fermented seasoning before the salt, keep the quantity small outside its home cuisine, and do not boil the miso.
The good version is the one you can make on a Wednesday.
Questions readers ask
Can I use soy sauce instead of salt?
Partly. It brings salt plus savoury depth, so it does more than salt, but it also adds colour and its own character. Add it first, then judge whether more salt is needed.
Why does fish sauce not make food taste of fish?
Cooking mellows it considerably, and in small amounts what remains reads as savoury depth rather than as fish. Most people cannot identify it in a finished dish.
