Katsuo-bushi

Katsuo is a medium-sized tuna which is in season from early summer to autumn. The fish is boiled and dried and then allowed to ferment and soften inside wooden boxes. This results, of course, in the growth of mold which is scraped off. Katsuo-bushi is used in various ways. It may be shredded and used to season takikomi-gohan (rice cooked with vegetables and seasonings); it may be sprinkled over white rice, tofu or vegetables, or it may simply be served as a side dish with soy sauce.

Another use is in ochazuke. You take shredded katsuo-bushi and put it onto a bowl of rice and then pour in hot tea.

Katsuo-bushi, even though it is formed from fish, is referred to as a seasoning. It dates back to a time before the Meiji Restoration in 1868.

It is also used to make up fish stock, a basic flavoring ingredient. The katsuobushi is used along with kep.