Fish Sauce and Fermentation: The Quiet Backbone of Thai Cooking
Ask most people what makes Thai food taste like Thai food, and they'll say chilli, or lemongrass, or coconut milk. Few people mention the ingredient doing more work than any of them.
Fish sauce.
It's rarely the star of a dish, but it's almost always there in the background, and without it, Thai food wouldn't taste like Thai food at all.
What Actually Is Fish Sauce?
Fish sauce is made by fermenting fish, usually anchovies, with salt over several months. The liquid that results is deep amber in colour, intensely savoury, and surprisingly complex once you get past the smell.
It's not used for its fishy flavour on its own. Used properly, it doesn't taste "fishy" at all. It brings a deep, savoury depth, the same kind of role soy sauce plays in Chinese cooking, or Parmesan plays in Italian cooking. It's there to round out and deepen everything else in the dish.
Fermentation Runs Through Thai Cooking
Fish sauce isn't the only fermented ingredient in Thai and Isan kitchens. Fermentation is a long-standing part of how food has traditionally been made and preserved across the region, long before refrigeration existed.
A few examples found across Thai and Isan cooking:
Fish sauce, the everyday seasoning behind most savoury dishes
Shrimp paste, used in curry pastes for a deep, savoury base
Pla ra, a stronger, more traditional fermented fish paste common in Isan cooking
Fermented soybeans, used in some regional dishes for extra depth
These ingredients were originally a way of making food last, preserving the catch or harvest before it spoiled. Over generations, they became central to the flavour of the cuisine itself, not just a way of keeping food edible.
Why It Matters for Balance
Thai cooking is built around balancing sweet, sour, salty, spicy and savoury in a single dish. Fish sauce is usually the ingredient supplying the salty and savoury side of that equation.
Without it, a curry or stir-fry can taste flat, even if every other ingredient is right. It's easy to underestimate an ingredient that doesn't announce itself, but take it out, and the difference is obvious.
Where You'll Find It on Our Menu
Fish sauce appears across much of our menu, from curries to stir-fries to dressings. A few places where it plays a key role:
Papaya Salad, where it's pounded together with lime, chilli and palm sugar
Green Curry and Red Curry, where it deepens the coconut base
Pad Thai, where it's part of the classic sweet, sour, salty balance
If you have a fish allergy or intolerance, it's worth telling us when you order, since fish sauce appears in more dishes than the name might suggest.
A Small Ingredient, A Big Difference
Fish sauce and fermentation rarely get the attention chilli or coconut milk get, but they're just as much a part of what makes Thai food taste the way it does. It's a good reminder that some of the most important ingredients in a cuisine are the ones working quietly in the background.
Taste It for Yourself at Kat's Oriental Cuisine, St Albans
Every dish at Kat's Oriental Cuisine is made using the same traditional ingredients and techniques that have shaped Thai and Isan cooking for generations, fish sauce included.
Browse the menu or explore the Dish Guide, and let us know if you have any questions about ingredients or allergens.
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