Nam pla is the salt of Thai cooking — understanding it transforms how you eat and cook Thai food.
Fish sauce is fermented fish liquid — anchovies or other small fish packed in salt, pressed and matured for months or years; the result is intensely savoury umami liquid.
Good quality fish sauce adds depth and salinity without tasting specifically of fish; the fermentation transforms the protein into something more complex.
Premium fish sauces (Megachef, Tiparos) are more complex and less aggressive; budget sauces are saltier and one-note; worth spending slightly more.
In almost everything — marinades, dipping sauces, stir-fries, salad dressings, soups; added at the table as a seasoning; the baseline of flavour in nearly every Thai dish.
There's no real substitute — soy sauce gives saltiness but lacks the fermented complexity; vegetarians can use coconut aminos or mushroom-based vegan fish sauce.
