One of the great historical milestones of East Asian cooking was the harnessing of the mold Aspergillus oryzae in China some 300 years before the birth of the historical Jesus. Over time, the mold made its way across the sea to Japan, where it became the culinary sine qua non known as koji. Like yeast in the west, which has brought us those great necessities of life, bread and beer, koji has provided the Japanese with the means to create their own staples, turning soybeans into shoyu and miso, and rice into sake, mirin, and vinegar.
This kind of primordial ooze is exactly the sort of thing that tends to be ignored, but it is enjoying a fashionable moment in Japan these days in the form of shio-koji, the kitchen-ready Aspergillus oryzae made from a fermented mixture of rice malt, sea salt, and water. Those interested in starting from scratch can find basic recipes online, but with it already in hand, acquired on a recent trip to H-mart, I was impatient to taste the deep flavors of old Japan, mixing them with sliced cucumbers, at the ratio of 1 tablespoon of shio-koji per 100 grams of the vegetable. The next morning, over a bowl of steaming gohan I ate deeply, smiling, knowing that this was only the beginning. The same technique could be easily applied to virtually any pickling vegetable, from the limp daikon in the bottom of the refrigerator to the Chinese cabbage I never can seem to finish. Deeper still are the shio-koji marinades for meat and fish, left overnight to macerate and truly develop the flavor. Now we’re getting somewhere.