Ohitashi (spinach with dashi dressing)

At the heart of so much of Japanese cooking is the fragrant broth called dashi. And at the heart of dashi are the delicate pink petals of katsuobushi, shaved flakes of dried bonito fish.

When steeped with the dried seaweed called konbu, katsuobushi gives dashi its irresistible aroma and deep umami flavor. Despite being made in minutes, the stock is the foundation of many Japanese dishes -- miso soup, salad dressings, sauces for noodles, even meat stews.

“Dashi is like the key actor in a movie,” says 83-year-old Chobei Yagi, whose 275-year-old store, Tokyo’s Yagicho Honten, specializes in katsuobushi and other dried foods. “But dashi always plays the supporting role, never the star.”

Most katsuobushi today comes pre-sliced in plastic bags, which is convenient and allows one to make dashi from scratch in less than 15 minutes, but there is another level of truly great katsuobushi -- artisanal arabushi-style katsuobushi and the maturer karebushi- and hongarebushi-style katsuobushi. These are sold in thick blocks, with brown surfaces coated in sun-dried mold. They look more like works of art than food, and maybe they are.

Katsuobushi was originally called kata-uo, or “hard fish,” and at one time every home cook owned a wooden plane, called a katsuobushi kezuriki, to shave what was needed. Store-bought sliced katsuobushi has now become the norm. In the United States, we almost always find only sliced katsuobushi; there just is not enough demand for the old-fashioned whole stuff to import it. It is mostly at specialty stores in Japan, such as Yagicho, where you can buy katsuobushi whole.

And it must be said that while there is nothing that can beat the tantalizing fragrance of freshly shaven bonito flakes, the modern method of packing is so advanced, the sliced petals do taste pretty darn fresh.

The most popular, multipurpose dashi is made with a combination of dried bonito flakes and konbu. The naturally occuring inosinic acid in katsuobushi and glutamic acid in konbu have a synergistic effect on flavor. “One plus one becomes three or more on the umami scale,” says Yagi.

Natural flavors

In modern times, Yagi laments that excessive use of oil, salt and chemically seasoned foods are making Japanese people forget the natural flavors of foods like katsuobushi. “There is nothing so delightful as food made under the sun,” he says.

One place that really cares about preserving the artisanal katsuobushi tradition is the city of Yaezu, Shizuoka, on Surugua Bay near Mt. Fuji, about an hour’s bullet train ride from Tokyo. The production of katsuobushi is one of Yaezu’s main industries; the city has designated the art of making it the artisanal way, mukei bunkazai, or a living cultural treasure.

About 100,000 to 120,000 tons of frozen bonito (also known as skipjack tuna) caught in the South Pacific and frozen on the boat, are brought to the port of Yaezu annually. The imported fish is favored over domestic Japanese bonito because of its lower fat content, which makes the katsuobushi taste milder and less fishy.

Tokuya Kuno, just over 30 years old, is president of Shin Marusho, his family’s 75-year-old katsuobushi factory based in Yaezu, which employees about 80 people. He grew up watching his father and grandfather make katsuobushi and never thought of becoming anything but a katsuobushi producer.

Kuno’s grandfather developed the award-winning Suruga Fubuki (Storm of Suruga) brand. The bonito flakes are light and delicate, resembling the fragile petals of cherry trees in springtime. About 80% of Shin Marusho’s katsuobushi product is the smoke-dried arabushi predominant in the Japanese marketplace.

To make arabushi, the bonito is cut up and cooked, then the fat, scales and bones are removed carefully (and used for fish extracts and fertilizer -- “nothing is wasted,” says Kuno). The fillets are then smoked slowly over mostly oak wood at varying temperatures for several days, with rests in between. The bonito, which can be as large as 6 pounds before cooking, shrinks by about 20% by the time the drying process is complete. On a busy day, one katsuobushi worker may gut, slice and clean as many as 150 bonito.

Different methods

While arabushi takes about 30 days to complete, karebushi and hongarebushi are made by processing arabushi several steps further. Arabushi is reshaped, the “tar” that coats the surface after cooking is removed and then the exterior is deliberately innoculated with a beneficial fungus, aspergillus glacus, in order to reduce the moisture further. The fungus is shaved and the fish is sun-dried repeatedly, three times for karebushi and even more for hongarebushi, taking as long as six months for the block to reach its full maturity.

Karebushi and hongarebushi are favored for the full and elegant aroma they give dashi. Arabushi has a smokier smell; it’s the most popular katsuobushi and is favored by soba and tempura chefs.

Katsuobushi and konbu dashi are made with katsuobushi and a piece of konbu seaweed, which are sold by type -- hidaka, raus, rishiri -- or as dashi konbu. Choose konbu that has some thickness and doesn’t look wafery and fragile. Basically, the two ingredients are steeped in hot water and strained from the broth.

Making fresh dashi is about as easy as infusing tea leaves to make a cup of tea. No wonder miso soup, which is primarily made from dashi, is traditionally served in Japan as a quick breakfast soup.

Katsuobushi primer

There are several types of katsuobushi that can be used for different purposes. The best will have light pink or beige shavings that will be slightly shiny. After the packages are opened, the katsuobushi will begin to oxidize and go limp, and the color becomes dull. Katsuobushi is best stored in the freezer.

Hanakatsuo is thin petals that resemble large wood shavings. Some contain chiai (dark meat).

Shaved karebushi makes a flavorful stock full of aroma. It comes with or without chiai. The lighter-colored shavings are suitable for making clear dashi -- ichiban dashi. The darker shavings are suitable for miso soups, simmered dishes and dressings.

Shaved arabushi is the most common type of katsuobushi found in the U.S. and is suitable for making soups, sauces and dressings. The more chiai you see in the shavings, the stronger the flavor.

Arakezuri has thicker shavings than hanakatsuo, with more chiai. Arakezuri produces a rich, strong dashi that is suitable for making braised dishes.

Itokezuri has the thinnest shavings. They are suitable as a garnish for salads and tofu.

Dashi pack is pre-shaved and partially pulverized katsuobushi that is sold in tea bags. It is very popular among Japanese cooks because it is easy to use. It is often combined with other dried ingredients such as konbu, shiitake mushrooms and other fish, such as sardines and mackerel, for a deeper umami flavor.