Sticky natto on top of a bed of white rice is a staple in Japanese homes and restaurants.

“Fermented soybeans” may not sound like the most appealing snack, and Japan may not quite have the strong (pungent?) reputation of its Korean neighbors when it comes to the process of fermentation. And yet natto is one of the country’s most popular snack foods, enjoyed both at home and in a large number of restaurants serving Japanese cuisine. Just take a look at the appetizers section of the menu during your next visit to a neighborhood Japanese joint — even the most simple of them are likely to feature the dish in some form.

According to Tomonori Takada, the president of Ootoya America (a restaurant serving Japanese comfort food, currently operating three locations in New York City), the most common way to eat natto is to put it on top of white rice after mixing it with soy sauce. It is most often eaten for breakfast, with some people consuming it on a daily basis.

Takada speaks highly of natto’s purported health benefits. It is perhaps best known for the enzyme “nattokinase,” which helps thin the blood and prevents blood clots. Soy isoflavones from the beans promote a strong metabolism while strengthening skin and hair and keeping cholesterol levels low. Additionally, natto is rich in minerals such as calcium, iron and magnesium, as well as fiber and vitamin B2. Takada points out that these health benefits — and the flavors — are enhanced when the dish is stirred well (it is said that natto tastes best after being stirred 400 times).

The process behind making natto is not terribly difficult. First, leave the soybeans soaking in water, allowing them to absorb lots of it. Proceed to steam the beans (usually with a pressure cooker) before spraying natto-kin (bacterium Bacillus subtilis) on them to start the fermentation process. Allow them to rest in a 104°F room or space for about one day, then move them out to let them cool and place them in the refrigerator for a few days to age.

hanabi don
Ootoya’s “hanabi don” bowl with natto, chopped okra, grated Japanese yam and high-quality sashimi.

The fermentation process breaks down the protein of the soybeans, which makes it easier for the body to digest and absorb. Fermentation produces vitamins and enzymes, which creates the unique smell and texture of the dish. It also enhances the nutritional values of the soybeans to the highest degree, says Takada.

In addition to serving natto simply over rice, Takada suggests adding soy sauce and Japanese mustard to the two, along with a poached egg and bonito flakes. The combinations are somewhat endless, as the dish also pairs well with chopped okra, Japanese yams and high-quality sashimi. Natto can also be found in tamagoyaki (Japanese egg omelet).