One of the essential ingredients in Japanese cuisine, katsuobushi or okaka refers to dried, fermented, and wood-smoked skipjack tuna. It is typically available pre-packaged in the form of delicate shavings which are used for imparting not only an intense umami flavor to various dishes but also the so-called kokumi - another taste sensation that can be described as heartiness and mouthfulness.
The production of katsuobushi is known to be complex and time-consuming, which contributes to its price tag. Also, the expensive skipjack tuna is sometimes substituted with its less pricey relative called bonito fish, which is why katsuobushi is often dubbed bonito flakes, and even though real katsuobushi is a far more superior product, both names are used interchangeably.