Koji is the name for the mold used in making soy sauce, miso, and other fermented foods and beverages. It can also be used as an ingredient in dishes, sauces and marinades.
Koji was first used in the production of fermented food in China over 9000 years.
You can purchase koji in the form of rice koji, steamed rice that has been inoculated with koji spores and then dried.
Shio koji is a seasoning made with rice koji mixed with salt and water. It can be used in marinades, and to season and tenderize meat or fish.