koji

Japanese; koji mould (Aspergillus oryzae) grown on roasted cereal to provide a starter for fermentation to produce natto and mirin.

[koh-gee] A fermenting catalyst known as Japanese "yeast," used in making myriad products including amasake, miso, sake, soy sauce and tamari. Koji is made from either beans or grains that have been inoculated with the mold Aspergillus. It's available in Asian markets and many natural food stores. Store in the refrigerator for up to 1 year.