Katsuobushi is the Japanese name for a preparation of dried, fermented, and smoked skipjack (bonito) tuna. 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. Larger, thicker shavings, called kezurikatsuo are used to make the ubiquitous dashi stock. Smaller, thinner shavings, called hanakatsuo, are used as a flavouring and topping for many Japanese dishes, such as okonomiyaki. Traditionally, large chunks of katsuobushi were kept at hand and shaved when needed with an instrument called a katsuobushi kezuriki, similar to a wood plane, but in the desire for convenience this form of preparation has nearly disappeared. Katsuobushi, however, retains its status as one of the primary ingredients in Japanese cooking today.
Katsuobushi's umami flavour 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.
When hanakatsuo is added as a topping to a hot dish, the heat has the effect of making the flakes move as if dancing; because of this, katsuobushi topping is also known as dancing fish flakes.
Other than the main ingredient of dashi stock, other popular uses of katsuobushi include:
- As a stuffing for rice balls (onigiri).
- As a seasoning for cold tofu hiyayakko along with grated ginger and spring onions.
- As a topping for rice (called furikake).
- Sprinkled with sesame seeds and chopped nori atop cold soba noodles.
- As a topping on takoyaki and okonomiyaki.
- As a seasoning on century egg along with sesame oil and soy sauce.
- As a high-protein treat for cats sold at pet stores.
- Katsuobushi was the inspiration for the title of the John Lennon album Shaved Fish.