Fish Saucealso: น้ำปลา · nước mắm · patis
Fermented anchovy liquid — Southeast Asia's primary salt source and the umami spine of dozens of national cuisines.
Origin
Roman garum, fermented in earthen jars on the Mediterranean coast, was the same idea two thousand years ago. The Vietnamese island of Phú Quốc, the Thai coast at Trat, and the Filipino province of Pangasinan are the three most respected production regions today.
What it tastes like
Salty, deeply umami, slightly sweet, slightly funky. The good stuff smells of the sea and faintly of cheese; the bad stuff smells like a chemistry experiment. Always taste-check a new bottle.
How it's used
Almost everywhere. As a finishing salt for soups (pho, tom yum). In dipping sauces (nước chấm, naam pla prik). In marinades, in stir-fries, in caramels, in the dressing for som tam.
Buying
Look for short ingredient lists: anchovies, salt, water. Optional: sugar. Phú Quốc and Sông Cầu Vietnamese sauces are gold standard for nước mắm. Megachef and Squid for Thai. The cheaper bottles are diluted and over-sweetened.
Substitutes
There is no honest substitute. Light soy + a pinch of anchovy paste approximates the flavour but loses the depth. Vegan substitutes (tamari + dried mushroom) are not the same dish.
Storage
Pantry, sealed, indefinitely. The flavour mellows over the first six months and is best between 6 months and 3 years.