Miso is magical. Not just for its ability to instantly add buckets of flavour to a dish, but for its simplicity.
In Japan, a deeply satisfying meal can centre on something as simple and unassuming as a bowl of rice and a dab of miso. Miso brings salt and umami to a completely blank canvas and, when joined by pickles and miso soup, becomes emblematic of the Japanese dining psyche. Each variety tells its own story – not just of provenance, but of the country’s diverse ingredients and techniques surrounding this beloved, ancient ferment.
Miso is also surprisingly simple to make, requiring just three ingredients, plus a fermentation container and a bit of patience. You mash together boiled (and cooled) soybeans, salt and rice koji, then pack it into a jar and leave it to ferment at room temperature. Depending on what you’re making, that could mean anything from a few short weeks or several years. It’s that straightforward.
The type of miso – saltier or sweeter, red or white – depends on the balance of soybeans, salt and rice koji. Rice koji is the starter culture not only for miso, but for a host of other fermented staples: shoyu (soy sauce), rice vinegar and sake. It’s the interplay of these three ingredients that dictates both the length of fermentation and the final flavour.
Kenji Morimoto
Thanks to its salt content (typically 5–13%), there’s plenty of scope to experiment safely. The salt shapes the taste, but it also controls the speed of fermentation – the higher the salt, the slower the fermentation – and keeps unwanted bacteria at bay. A common challenge is surface yeast, which can appear despite standard precautions like topping the miso with a layer of salt or using parchment as a barrier.
But I don’t see this as a flaw. Miso making, like so many kitchen ventures, is an education in what works, what doesn’t and how you adapt your methods to your own surroundings. What sets miso apart is that the microbes on our hands become part of the miso itself – a true act of communion. I remember making a batch with my parents the first time I saw them after the pandemic, our hands mashing soybeans to the soundtrack of easy conversation.
There’s something inherently human about fermentation as a process. It’s tangible, social, and marks the passage of time. This communal practice exists across cultures, each adding its own touch to the shared act of transforming humble ingredients into something far greater than the sum of their parts.
To learn more about miso making and fermentation, check out Kenji (@kenjcooks)’s debut cookbook, Ferment (Pan Macmillan).
