Fish sauce

A powerful thin brown sauce used in numerous Asian cuisines. It is made by fermenting small whole fish in brine and drawing off the liquid, which is then bottled. It smells pungent and tastes very salty, although cooking greatly reduces its ‘fishiness’ and simply adds a richness and a layer of flavour to cooked dishes. It's frequently used in Thailand, where it is known as nam pla. In the Philippines it’s known as patis, in Vietnam it's called nuoc nam, and it's known as shottsuru in Japan.

(Source: BBC)