Soy sauce (English) , soya sauce (Commonwealth), or shoyu (Japan) is a fermented sauce made from soybeans, roasted grain, water and salt. Soy sauce was invented in China, where it has been used as a condiment for close to 2,500 years. In its various forms, it is widely used in East and Southeast Asian cuisines and increasingly appears in Western cuisine and prepared foods.
Soy sauce is an essential for Chinese cookery.
Light or fresh soy sauce A thin , opaque, dark brown soy sauce. It is the main soy sauce used for seasoning, since it is saltier, but it also adds flavour. Since it is lighter in colour, it does not greatly affect the colour of the dish. The light soy sauce made from the first pressing of the soybeans is called first soy sauce or referred to as premium light soy sauce.
Touchou is sold at a premium because, like extra virgin olive oil, the flavour of the first pressing is considered superior. An additional classification of light soy sauce, shuanghuáng, is double-fermented to add further complexity to the flavour. These latter two more delicate types are usually for dipping.
Dark/old soy sauce A darker and slightly thicker soy sauce that is aged longer and contains added molasses to give it its distinctive appearance. This variety is mainly used during cooking since its flavour develops under heating. It has a richer, slightly sweeter, and less salty flavour than light soy sauce. Dark soy sauce is partly used to add colour and flavour to a dish.
Dark soy is particularly good for marinades.