Katsuobushi, or dried bonito, is a key ingredient in Japanese cuisine. Unfortunately, in the West we can only get it in flakes—it’s still delicious, but it’s a bit like using pre-grated Parmigiano-Reggiano instead of getting a proper chunk off of the wheel. One of my missions in Japan was to find the real thing. Hearing of my quest (and thinking that I was perhaps ever so slightly weird), my friend Tetsuo-san arranged for us to visit a shop in his neighborhood in Yokohama, Nagano Katsuobushi Ten.
To the uninitiated, katsuobushi might not even look like fish. It might be mistaken for, say, a stick. Or a rock. But no, it’s really tuna (skipjack tuna, to be precise). At a typical katsuobushi shop, you’ll see a wide variety for sale, ranging in price from around ¥1,500 a kilo to over ¥5,000. Mr. Shigekazu Ichinose (pictured), proprietor of Nagano Katsuobushi Ten, explains that this is due to different grades of fish—the best fish for making katsuobushi is young tuna that has a final water content of around ten to 15 percent; lower grades have a higher content of both water and oil. Each piece represents one-quarter of a fish, so there are two pieces from the back and two from the belly. Since the belly has a higher fat content, it produces lesser-quality katsuobushi.
The process of drying the fish requires a total of five to six months. After the fish is caught and gutted, it’s boiled to activate certain bacteria and enzymes in the flesh, then dried in the sun. The boiling and drying process is repeated several times, and then the fish is steamed together with a wood called narakunugi-sakurazai, which imparts a subtle aroma. At this point the fish is called harakabushi, which is mildly scary-looking, as you can see in this photo. Harakabushi can be eaten as is, in udon or soba, and in fact, a similar product is found in other areas along the tuna’s migratory route, such as Papua New Guinea and the Maldive Islands. Only the Japanese, however, age it further to make katsuobushi, which has a more refined and complex flavor.
To achieve this, the harakabushi is aged in high-humidity storage so that it develops a fine mold, which Ichinose-san compares to the bloomy rind on cheese. It’s periodically taken out, dried and placed back into storage, and eventually it ends up looking like the examples in this photo. Sometimes you’ll see it with more mold, and sometimes it’s sold with the mold wiped off, but Ichinose-san says that the mold on the best katsuobushi is very fine and thin. Here are two examples of top-grade katsuobushi: the piece on the right is from the back, while the piece on the left, with a shallow depression running along the length of it where it was gutted, is from the belly.
The piece that he selected for me (from the back, of course) was long and straight—apparently the straight ones are better than the curvy ones, but I don’t know whether this is because it’s easier to shave or for some other qualitative reason. To use it, I imagine that one could employ a truffle shaver or some other similar implement. However, the proper tool is called a katsuobushi-kezuriki, which I was able to purchase from his friend down the street. It’s a box fitted with a sturdy blade that looks like a carpenter’s plane—you hold the katsuobushi lengthwise and shave micro-thin slices that fall down into the drawer below. The thickness and width of the slices can be adjusted according to how much pressure you apply. Now if I can just find a bit of grand cru kombu, or dried kelp, I can become a dashi-making fiend....