Soy sauce, a condiment quintessentially associated with Chinese cuisine, is known to have originated in China around the 2nd century CE. It is made from the fermented paste of boiled soybeans, roasted grain, brine, and the fungi Aspergillus oryzae or Aspergillus sojae.
There is a distinct different between light soy sauce and dark. Similar to the varying degrees of classifying olive oil, light soy sauce comes from the first pressings of the soybean, and the premium first pressing is known as tou chou while the light sauce from the subsequent pressings is called shuang huang. The delicate flavour of tou chou light soy sauce makes it best suited to seasoning lightly flavoured dishes while the shuang huang variety is double fermented, has a more complex flavour, and is mostly reserved only for dipping.
Dark soy sauce is older, and, as the name suggests, is darker and thicker. It starts off as light soy sauce but goes through a prolonged process of aging and may contain either added caramel colouring or molasses, or both, to give it its distinctive appearance. Dark soy sauce is used mainly for cooking. It is richer, sweeter, and less salty than light soy sauce, and is more commonly used as part of the cooking process but also less commonly after cooking to add colour and flavour. Varieties of dark soy sauce include mushroom dark soy – where paddy straw mushrooms Volvariella volvacea are added and the sauce exposed to sunlight – and thick soy sauce, which has been thickened with starch, sugar, and monosodium glutamate, and occasionally spices.
Soy sauce spread to other cuisines throughout Asia and different varieties (not covered on this page) exist in the cuisines of Japan, Indonesia, Korea, Burma, Philippines, Malaysia and Singapore, Taiwan, Vietnam, and Hawaii.