Bonito is a kind of tuna, and Katsuobushi is dried, smoked bonito. Katsuobushi is often used as flakes shaved from a piece of dried fish. This is actually Kezuribushi, but we still call it Katsuobushi. Some Katsuobushi is only smoked and dried, but the real Katsuobushi is smoked and then ripened with a special kind of mold for months to a couple of years. Katsuobushi is usually sold as flakes or shavings in a package today, but you can buy a chunk and shave it yourself with a Katsuobushi plane if you would like to make your own.
Katsuobushi has a smokey savory taste that is a great accent for many Japanese dishes. Because dried bonito is packed with lot of umami (savory taste), it is perfect for making Dashi (fish broth) with which is a crucial component for Japanese cooking. Katsuobushi also can be used as is, sprinkling on simple vegetables to give a deeper flavor instantly.
We have recipes for both Dashi and Ichiban Dashi (combination of Katsuobushi and Kombu dried kelp). While Katsuobushi is a common flavor for Dashi, you can use only Kombu if you don’t want to use or don’t have any Katsuobushi.