It takes 6 months to make fermented black beans.
A byproduct of soy sauce, this product begins by inoculating black soybeans with koji, the spore that works its magic on Japanese staples like miso and soy sauce. After mixing the black beans with water and salt—and allowing them to rest for 180 days in earthenware vessels—some beans go on to become soy sauce, while others are reserved as a salty, funky, umami-forward cooking ingredient.