Or it should be - several manufacturers sell products labelled as soy sauce which are produced in a few days using chemicals such as hydrochloric acid.

When choosing soy sauce, look for the words naturally brewed on the label and avoid any whose ingredients list includes artificial colourings.

Shoyu sometimes used to describe the Japanese version. Tamari is made without malted grain. The Chinese produce light and dark versions with specific culinary duties. Ketjap manis is a sweetened variety from Indonesia.

Essential for all sorts of Chinese and Japanese cooking, soy sauce is also good used as a general seasoning in Western dishes, especially vegetarian ones. Add to soups and stews to boost their flavour, or use in salad dressings. It is good sprinkled on boiled or poached eggs.