On Food and Cooking

thousand years ago in the freshwaters of
southwest China and the Mekong River
region. It then spread to the coastal deltas and
was applied to ocean fish. Two broadly
different techniques evolved: simply salting a
mass of small fish or fish parts and allowing it
to ferment; and salting larger fish lightly, then
embedding them in a fermenting mass of rice
or other grains, vegetables, or fruits. In the
simple fermentation, the proportion of salt is
usually enough by itself to preserve the fish
from spoilage, and bacteria are important
mainly as flavor modifiers. But in the mixed
fermentation, a smaller dose of salt preserves
the fish for just a few weeks while the plant-
based ingredients feed the same microbes that
sour milk or turn grape juice into wine. The
fish is then preserved by the microbes’ acids
or alcohol, and flavored by the many by-
products of their growth.
From these simple principles, Asian
peoples have developed dozens of distinctive