And how is the foundational Japanese paste actually made?
Miso is spreadable umami, a sweet and salty paste that adds savory depth to soup bases, cuts of fish, and vegetable braises. But what is it, exactly? There are two big components: soybeans, which are full of proteins that in turn contain amino acids, the essential molecules of umami flavor, and koji, a mold cultured from a mix of grains like rice and barley. Add mold to beans, keep them in the right climate conditions, and watch the slow, controlled rotting break the beans down to a richly flavored paste.
In other words, it’s a fermented food just like pickles and beer, and like those lovely things, you can make miso at home. Unlike pickles and beer, sourcing the right ingredients for miso, and maintaining the proper climate for fermentation rather than spoiling, is pretty challenging. So if you’re an advanced fermenter, find some trustworthy recipes and give it a shot. But the stuff at Japanese specialty stores is pretty good all on its own.