Dec 05,2024
We revisited the Kome-no-Hana koji [rice malt] outlet in Chigasaki, Kanagawa, on a day in October, as signs of autumn were beginning to make their presence felt. The purpose of our visit this time was to talk with Kumazawa Yumiko, wife of koji-maker Kumazawa Hiroyuki, about the koji-based seasonings that are a staple in their home. Yumiko started cooking using koji well before Hiroyuki started the koji outlet, and she now runs workshops on making koji seasonings at Rivendel, the farm the couple operate and where they have nurtured their lifestyle. In this article, we asked her how to make onion koji and how best to use koji seasonings.
The Kumazawas’ field produces a variety of fruits and vegetables throughout the seasons. When we visited, the chestnut burrs had just burst open, and the pomegranate shrubs were bearing their red fruit. And although the autumn winds were later than usual this year, the persimmons were starting to take on their bright colors.
“I love being able to enjoy seasonal fruits and vegetables all year long,” says Kumazawa Yumiko. On the other hand, she laughs, because they collect the same fruits and vegetables in one harvest, she has to get creative and cook them all at once while they’re still delicious. A go-to recipe in their household is a simple soup that features koji seasoning. On the day of our visit, she had made pumpkin potage soup for us.
“We gather a lot of pumpkins during this season, so this potage soup appears on our dinner table a lot. Besides pumpkin, I often make this potage soup with other vegetables such as turnips, carrots, and sweet potatoes. It tastes delicious year-round — chilled in summer and hot in winter.”
Onion koji is key to the taste of the Kumazawas’ homemade potage soup. Yumiko shared with us how to make onion koji.
On the left is the fermented onion koji. It changes gradually over one or two weeks from the color when first prepared (the mixture on the right) to a brownish color. The onion koji will also begin to take on a consommé-like aroma.
“For pumpkin potage soup, either steam or microwave the pumpkin with the skin on to soften it and then mash it. Mix in unflavored soy milk to the mashed pumpkin until it reaches the desired consistency, and season with onion koji. It tastes great even if you substitute milk or fresh cream in place of unflavored soy milk. For a quarter of a whole pumpkin, add about two tablespoons of onion koji.”
Yumiko says that drizzling on a little olive oil to finish further boosts the flavor.
“My son won’t eat a salad or vegetables on his own. So when I make a soup with seasonal vegetables, I serve him a big bowl of it. It’s easy to make and you can eat up the entire vegetable. Because it’s high in nutritional value, it’s a dish I want my kids to actively eat.”
After she began regularly using koji seasonings, Yumiko’s physical condition improved.
“I’ve always been very sensitive to the cold. On days when my husband and kids would wear light clothes, I would still be in a down jacket. And I would frequently get colds as the seasons changed, and I was always putting on compresses to ease shoulder stiffness. But once I started using koji seasonings and changed my diet, my health improved bit by bit without me noticing it. Then, all of a sudden, I realized I wasn’t catching colds anymore.”
Yumiko always has homemade salted koji, soy sauce koji, and onion koji on hand. She also says she is never without miso and amazake (a sweet drink made from fermented koji). She was already familiar with koji seasonings before her husband, Hiroyuki, began running the koji outlet in Chigasaki.
“I began using salted koji when it was getting a lot of attention in cookbooks and on cooking shows. I got into it because of the buzz around it, and I used it to season fried chicken. After that, I gradually became aware of the benefits of not just salted koji, but also soy sauce koji and onion koji, which led me to use them in my everyday cooking.”
Later on, Hiroyuki opened the koji outlet, making koji an even more familiar presence in their household. They make koji seasonings throughout the year and use either miso or one of the three koji seasonings in nearly all their cooking. (See this webpage for instructions on making salted koji and soy sauce koji at home.)
“You can take the onion koji recipe and add celery and carrots to the onions to make a seasoning that people call consommé koji. Or you can switch out the onions for green onions and make Chinese-flavored koji. Many people like adding things like garlic to onion koji as well. In our home, however, after experimenting with different variations, we’ve settled on the basic onion koji. Onion koji is easy to use because it goes well with many dishes, and when I want to change up the flavor, I simply add celery or garlic to the dish itself.”
“There are many things to like about koji seasonings, but one that I love are the complex flavors that the power of koji creates. Koji seasonings on their own add umami and body that make food taste better, without needing to combine a number of different seasonings. When making a white sauce, for example, seasoning it with onion koji brings out a real deep richness. You can prepare a truly delicious white sauce by adding a small amount of butter to soy milk and then seasoning it with onion koji — no thick fresh cream needed. Being able to whip up a white sauce easily at home is convenient when making dishes like doria rice gratin.”
The Kumazawas both highly recommend combining onion koji with either soy sauce koji or salted koji. These combinations are very handy when, for example, making dressings or sauces.
“I often make a Chinese dressing with onion koji and soy sauce koji, along with vinegar and sesame oil. And if I want it to taste even more Chinese, I’ll add minced garlic or ginger. You can use it as a sauce for Chinese-style fried chicken or pour it on chilled shabu-shabu hotpot dishes. It goes really well with meat and kids love it.”
Hiroyuki adds: “I’m a big fan of dressings made with onion koji, salted koji, and olive oil. If you make it with just onion koji, it tends to get too sweet. The salted koji balances it out and enabling the dressing to pair with nearly anything. Adding lemon to it is also delicious. It’s perfect for salads and sauteed meat.”
The couple says that koji does a lot more than just add saltiness. Koji produces complex flavors and richness that enhance the umami of vegetables and meat. With koji, you can easily prepare a feast.
Soy sauce koji, in particular, really comes into its own in the fall.
“For example, don’t you want to make takikomi mixed rice when fall comes around? In our house, we get this urge to make it as soon as fall comes. (laughs) If you make it only once or twice a year like us, then you might worry until it’s finally cooked whether you combined the soy sauce, saké, and other seasonings in the right amounts to get the flavor you prefer. However, seasoning takikomi mixed rice is a snap if you use soy sauce koji.”
Soy sauce koji has the saltiness of soy sauce to be sure, but it also has a sweetness along with the distinctive flavor of a fermented seasoning that can replace saké or mirin rice wine. This is why seasoning takikomi mixed rice with soy sauce koji on its own will turn out tasting great.
“We often cook things like mixed rice with mushrooms, mixed rice with salmon, and mixed rice with deep-fried tofu, canned tuna, and ginger. Add the ingredients and rice plus one tablespoon of soy sauce koji per 180 grams of rice. So for three 180-gram measures of rice, you would use three tablespoons. Three tablespoons might seem too much for some people, but remember you are not adding three tablespoons of soy sauce. The action of the koji ensures that it doesn’t become overly salty.”
Soy sauce koji is really useful in stir frying too.
“Soy sauce koji is helpful when making teriyaki chicken or ginger pork. You can get the flavor you want with just soy sauce koji, instead of using a variety of seasonings. Stir-fried pork will taste really good with just soy sauce koji, but if you also add onion koji, it will taste that much better. They add in sweetness and richness, as well as umami, so the combination of soy sauce koji and onion koji alone produces a really fine tasting dish.”
It is likely that some people will feel that making their own seasonings is difficult or takes too much time. However, Yumiko says she recommends koji seasonings especially to people who are busy or people who aren’t good cooks.
“Making koji seasonings is surprisingly simple once you try it. If you make a batch, you can store it in the fridge. They will definitely bring out more umami without needing a combination of seasonings, and you’ll immediately feel your cooking has gotten better. And they are easy to use. Where you would normally use salt or soy sauce, use salted koji or soy sauce koji, and substitute onion koji for consommé. Another point in their favor is they don’t contain any additives, so you get a truly natural flavor.”
Yumiko rarely buys specific seasonings for specific dishes anymore. She finds she can replace a great many seasonings with just three: salted koji, soy sauce koji, and onion koji.
“Koji seasonings work with Japanese, Western, and Chinese dishes equally well. They are very adaptable too. Once you’ve chosen a koji seasoning, you can tailor the taste by the oil you select, such as sesame oil or olive oil, and by adding or omitting garlic and chili peppers. There are so many combinations, you are sure to find your own preferred tastes.”
The Kumazawas started this year making doubanjiang — fermented chili bean paste — with koji and fava beans. Today, again, the Kumazawas’ dinner table is colored with dishes that make great use of seasonal vegetables and the power of koji.
Kome-no-Hana produces and sells koji, salted koji, and amazake and offers miso and soy sauce-making classes by appointment.
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