Where else but Japan would there be a national fungus? In their fermentation-friendly food and beverage culture, everything from soy sauce to miso is created through fermentation with help from koji, a fungus otherwise known as Aspergillus oryzae. Its value in sake brewing is what earned koji the national fungus designation from the Brewing Society of Japan.

The koji fungus currently resides at the intersection of diners’ fascination with fermentation and their deepening interest in Japanese cuisine, one that has expanded far beyond sushi to include ramen, izakaya, tonkatsu, bento boxes and more. Using koji in fermenting (and cooking) delivers a depth of umami flavor, that savory fifth taste (beyond sweet, salty, sour and bitter) that has gained attention as a way of providing robust taste and deep satisfaction with less (or no) animal protein.

PinKU chef delivers umami punch

“I have only 17 items in my pantry, all of which were things my grandmother used in her kitchen, and many of them have a direct tie to koji,” says Japanese-American chef John Sugimura, managing partner and executive chef at PinKU, a Japanese street food restaurant in Minneapolis, Minnesota. From his tiny storefront, Sugimura serves up Japanese specialties, many of which rely on the transformative power of koji to break down protein into glutamates, which increases umami flavor.

His Natto Fat Roll, for example, is the vegan equivalent of a spicy tuna fat roll, made with fermented soybeans. “Fermentation makes the soybeans sticky and tacky, and gives them a strong, pungent taste, but with the addition of green onions, mustard, sesame and chili oils, it really becomes something beautiful. It’s rolled with lettuce, avocado, radish and burdock root. It’s not only tasty—it’s rich in probiotics and has 21 grams of protein.”

Koji dishes on the menu

Chefs have been experimenting with new applications of koji, including the use of shio koji, a paste made of fermented rice granules and salt. The Japanese burger chain Mos Burger, which has 1,700 stores throughout Asia, features a shio koji burger as a popular special. Other chefs are using dehydrated rice inoculated with the koji mold to cure meats and season sauces. Chef Nick Blue at Sardella in Clayton, Missouri makes an umami-rich roast chicken with a koji rice rub.

In your own operation, try tossing some veggies in shio koji paste to create a speedy pickle. A bit of the paste also adds depth and umami flavor to just about any salad dressing. Or try it as an overnight marinade for chicken breasts for an easy oven roast with umami-packed flavor.