Katuobushi

Katsuo-bushi is one of the most basic elements of Japanese cuisine, and is a key ingredient in a wide variety of dishes prepared throughout the seasons. In simple terms, katsuo-bushi is a dried fish fillet, and is one of Japan's most traditional preserved food products.

It is made from bonito, a small fish similar to tuna, which is known as katsuo in Japanese. The word katsuo-bushi literally means "a lump (or knot) of bonito" but in common usage it refers to the extremely thin shavings taken from the extremely hard dried fillet using a very sharp planing device. In English, katsuo-bushi is commonly referred to as "dried fish flakes."

Nowadays, most people purchase pre-shaved katsuo-bushi in packages, and outside of high-end traditional Japanese restaurants it is quite rare to see a chef shaving katsuo-bushi for a dish. Freshly shaved katsuo-bushi, however, has a somewhat stronger aroma and a slightly sweeter taste since the dried shavings have yet to fully dry and oxidize. Still, most people cooking at home prefer the convenience of packaged flakes.

Katsuo-bushi is most commonly used to make dashi, a basic fish stock for various types of soups and seasonings. Very finely shaved katsuo-bushi is also used as a topping for boiled vegetables and other simmered dishes. In recent years, it has also been used to add a Japanese touch to western-style salads.

The flavor imparted by katsuo-bushi is very subtle, but rich and very protein-like. It has very little fat, and has almost no "fishy" taste. Rather, it is smooth and slightly smoky, and has a clean, satisfying aftertaste which is behind almost all Japanese boiled and simmered dishes. Some consider the prime stock made from katsuo-bushi to be the most delicious soup stock in the world.

While the taste of katsuo-bushi is clean and simple, the process used to make it is long and complicated. First of all, the fresh fish is cleaned and filleted, and the smooth, boneless fillets are boiled. Next, they are fermented with a special mold culture and heavily smoked. Oak is used to smoke the best grades of katsuo-bushi because it imparts a good flavor.

After smoking, the fillets are set out to dry. The mold fermentation works to remove moisture from the fish, in much the same way that the noble-rot mold removes moisture from grapes that are used in dessert wines. The fish also loses moisture during the smoking process.

These steps are repeated until the fish fillet is extremely hard. Striking two finished katsuo-bushi pieces against one another will make an almost ringing sound. They resemble smoothly sanded pieces of hardwood, and in a sense, can be considered "fossilized." This is why they can be kept in a cool, dry place for many years, although it is best to use katsuo-bushi within a year to enjoy the best aroma and flavor.

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