If you had to summarize Japanese cuisine in a single word, you would probably settle on “simplicity.” As in other areas of its culture, the Zen-inspired principle of less being more conspicuously applies to the nation’s food. By and large, Japanese chefs eschew complex combinations of ingredients, preferring instead simple cooking techniques that highlight the natural flavors of the finest seasonal fare. In line with that perspective, the cuisine tends to rely on just a small number of basic flavorings. Soy sauce and the fermented soybean paste of miso are familiar overseas. Less well known is the key condiment of mirin, which is a sweet alcoholic liquid flavoring. The other central element in the nation’s food is also not so recognizable outside the country, but Japanese cuisine just would not be the same without the stock called “dashi.” And that stock would not exist at all without the humble skipjack tuna.
Known as katsuo in Japan—and commonly mistranslated as “bonito” in English—skipjack tuna is used to make katsuobushi, which is indispensable in making dashi. For katsuobushi, the traditional method of curing skipjack can take up to six months. First, the fish is filleted into four pieces, which are boiled and then dried. After drying, the fillets are smoked over a hardwood fire for half a day and rested. The smoking can be repeated ten to fifteen times. When the smoking is completed, the fish is scraped clean, inoculated with the mold Aspergillus glaucus, cured and air-dried until it is as hard as wood, so hard in fact that it has been certified by Guinness World Records as the hardest food in the world. Katsuobushi also happens to look for all the world like a moldy block of wood—the diametrical opposite of anything that might conceivably get the stomach gurgling in anticipation of a repast.
After curing, the katsuobushi is ready to be shaved using the kitchen equivalent of a carpenter’s plane. With dashi, one of the most common methods involves heating the shaved fish in water together with kombu, a type of edible kelp, and then straining the resulting broth. There is no question about fresh shavings of katsuobushi producing absolutely the finest dashi. But nowadays, cooks in restaurants and at home frequently opt for convenience and thrift when they reach for prepackaged katsuobushi flakes or even dashi granules to make their stock.
Dashi finds wide employment in the Japanese kitchen. It is an essential ingredient in soups and is used to season boiled vegetables or as simmering liquid for such dishes as sukiyaki and one-pot stews. Almost transparent, thinly shaved curls of katsuobushi are employed to season and garnish hot and cold dishes. After being sprinkled over foods like fried noodles or okonomiyaki pancakes, the very thin shavings perform a little dance as they are moved this way and that by the heat. For experienced diners, the tiny dance can be a joy to behold; for uninformed neophytes, it can look unsettlingly as though something is still alive and wriggling on the plate.
But there is much more to skipjack tuna in Japan than a little terpsichorean flair and furnishing a condimental cornerstone of the nation’s cuisine. Even without undergoing its woody transformation into katsuobushi, the tuna is held in high esteem among gourmands, notably during the two seasons when the fish is considered at its peak. The first is when skipjack tuna migrate north from April to June to feed in cold North Pacific waters. These northbound fish, known as first skipjack (hatsu-gatsuo), are lean and delicately flavored. From September through November, the schools swim south to warmer waters again and are called returning skipjack (modori-gatsuo). The more concentrated flavor and richness of the well-fattened autumn catch is the finny preference among many aficionados.
Whether it is the first or returning variety, Japanese chefs often prepare fresh skipjack by quickly searing the long fillets over a hot fire (traditionally of rice straw) and quickly plunging them into ice water. This is known as tataki, and it ensures that while the outside is charred, the inside remains raw. The fish is then sliced and typically served with soy sauce, citrus vinegar, green onions, ginger and garlic.
In addition to the fine dining experience with skipjack tuna, there is a somewhat romantic side to the fish. The word ipponzuri has an attractive ring to it in Japanese today, even though it translates somewhat mundanely as “single-pole fishing.” The term conjures up images of the most artful, virile and perhaps most ecologically sound of all commercial fishing methods practiced in Japan. A dozen fishermen line up closely together in the gunwales of the fishing boat and cast their lines with un-baited hooks into a school of skipjack that has been worked into a feeding frenzy by flinging a few buckets of sardines over the water surface and spraying the water to create the illusion of sardines running at the surface. Skipjack are small for tuna, but they still weigh four to five kilograms, and the fishermen haul them out of the water in a high arch using four-meter poles with impressive rapidity and dexterity, landing the fish in quick succession. But perhaps even more impressive is how they manage to do all that without getting somebody’s eye out in the process.
At one time, skipjack tuna was not so highly regarded in Japan. The fourteenth-century author and Buddhist monk Yoshida Kenko in his famed Essays in Idleness wrote how among the people of Kamakura, when that town near today’s Tokyo served as the country’s capital, skipjack was so poorly considered that even servants threw away the heads without eating them. But by the Edo period (1603–1867), skipjack had undergone a culinary metamorphosis and achieved exalted piscine status. The preference then was definitely for the first skipjack. Such was the esteem of the fish that it even had marital repercussions, as evident in a saying of the time: “I’d pawn my wife for a taste of hatsu-gatsuo.”
David Capel is a journalist living in Tokyo.
First published on TJJ ONLINE October 9, 2018. Updated September 6, 2021