Bonito Flakes (Katsuobushi)
What it is
Skipjack tuna ("bonito") that has been simmered, smoked, and fermented into one of the hardest foods in the world, then shaved into translucent flakes. The cornerstone of Japanese dashi.
How it's made
Skipjack fillets are simmered, deboned, and repeatedly smoked (arabushi), then for the finest grade inoculated with ***Aspergillus glaucus* mold and sun-dried in cycles over weeks to months** (karebushi) — the mold draws out moisture and refines flavor, producing a fish loaf so hard it's shaved like wood with a katsuobushi kezuriki plane.
Flavor profile
Profoundly smoky, savory, faintly sweet; pure inosinate umami. The flakes "dance" in the heat of a hot dish.
Culinary uses
Steeped with kombu to make dashi, the foundation of miso soup, noodle broths, and simmered dishes; sprinkled as katsuobushi over okonomiyaki, takoyaki, tofu (hiyayakko), and rice.
Regional variations
Arabushi (smoked only) vs. karebushi/honkarebushi (mold-fermented, premium). Blended dashi often combines it with mackerel and sardine flakes.
Cultural & historical context
The mold-fermentation step makes katsuobushi a rare example of a fermented dried fish and a pillar of washoku (UNESCO-recognized Japanese cuisine) and the science of umami itself — inosinate was first studied through bonito.
Reference notes
Tags: `dried`, `smoked`, `fermented`, `fish`, `umami`, `japanese`. Related: kombu, niboshi, sababushi. Cuisine: Japanese. Links → Dashi, Kombu, Umami, Okonomiyaki. Dish impossible without it: real dashi.