Katsuobushi

Katsuobushi (鰹節; かつおぶし) (Chinese: 柴魚; chai2 yu2; lit. "firewood fish"), is the Japanese name for a preparation of dried, fermented, and smoked skipjack tuna (Katsuwonus pelamis, sometimes referred to as bonito). Katsuobushi and kombu (a type of kelp) are the main ingredients of dashi, a broth that forms the basis of many soups (such as miso soup) and sauces (e.g., soba no tsukejiru) in Japanese cuisine. It is today typically found in bags of small pink-brown shavings, looking somewhat like cedar shavings used to line the cages of pet animals, or the shavings of a plain wooden pencil. Traditionally large chunks of katsuobushi were kept at hand and shaved when needed with an instrument similar to a plane turned upside down, but in the desire for convenience this form of the food has nearly disappeared. Katsuobushi, however, retains its status as one of the primary ingredients in Japanese cooking today.

Katsuobushi's umami flavor comes from its high inosinic acid content. Traditionally made katsuobushi, known as karebushi, is deliberately planted with fungus (Aspergillus glaucus) in order to reduce moisture.

Uses

Apart from dashi, other popular uses of katsuobushi include:

As a stuffing for rice balls (onigiri).
As a seasoning for cold tofu (hiyayakko, 冷奴) along with grated ginger and Welsh onion (a type of spring onion.)
As a topping for rice (called furikake).
Sprinkled with sesame seeds and chopped nori atop cold soba noodles (zarusoba).
As a topping on takoyaki and okonomiyaki.
As a seasoning on century egg along with sesame oil and soy sauce.
As an ingredient in okonomiyaki

Trivia

Katsuobushi was the inspiration for the title of the John Lennon album Shaved Fish.
Katsuobushi can be written like this: 勝男武士, which, when translating the kanji, means literally "winning man samurai". As a result, it was a very popular food among the samurai.