Tuna, or bonito, is a type of fish. Dried bonito flakes are smoked Bonito fish flakes that have been dried. They resemble wood shavings in appearance. Katsuobushi-Dashi, the second most popular variety of Dashi (Japanese broth) for miso soup, is made with bonito flakes. Bonito flakes are also used to produce Ponzu sauce and onigiri filler.