Bonito Flakes (Katsuobushi): For Dashi, Okonomiyaki and Tofu

Flavor

Bonito flakes smell smoky and of fish. In the broth you taste less fish than you expect. They bring mainly umami from inosinate. Together with the glutamate from kombu, this gives dashi its typical depth. Plain on the tongue the flakes melt and taste salty and smoky, much like smoked ham.

Production

The starting product is the true bonito, also called skipjack (Katsuwonus pelamis), a small relative of tuna. Producers fillet it, cook the fillets in hot water and smoke them over a wood fire, often in many rounds over several weeks. That gives arabushi. For the top grade, karebushi, they also inoculate the blocks with a noble mold and dry them for months. In the end two blocks sound like wood when knocked together.

Japanese kitchens used to shave katsuobushi fresh every day with a shaving box. Today most cooks buy ready-shaved flakes, kezuribushi.

Types

• Hana katsuo: large, thin, pink-brown flakes. The standard for dashi and as a topping.
• Itokezuri: fine threads, decorative on tofu or vegetables.
• Atsukezuri: thick shavings for long-cooked, strong broths, for example for noodle soups.
• Small portion bags: 2 to 5 g per bag, handy for toppings, because the flakes lose aroma fast once opened.
• Other fish: Sababushi from mackerel or blends for udon broths taste stronger.

Dashi with bonito flakes

For a first dashi (ichiban dashi) you need 1 liter of water, 10 g kombu and 20 to 30 g bonito flakes, that is two to three big handfuls.

1. Steep the kombu in the water and heat slowly to just below a simmer, then take it out. The details are under Kombu.
2. Bring the water briefly to a boil, turn off the heat and add the bonito flakes all at once.
3. Steep for 1 to 2 minutes, until the flakes sink to the bottom.
4. Pour through a strainer lined with paper towel or cloth. Don't squeeze the flakes, or the broth turns cloudy and bitter.

With the spent flakes and the kombu you cook a second, stronger dashi (niban dashi) for miso soup and braises: add 500 ml fresh water, simmer gently for 10 minutes, add a handful of fresh flakes and strain. The recipe for Awase dashi shows all the steps, and Dashi and dashi powder explains the differences from instant powder.

As a topping: why the flakes dance

On hot Okonomiyaki and Takoyaki the flakes move as if they were dancing. The thin shavings draw moisture from the steam, soften unevenly and curl. On cold tofu they stay still: for Hiyayakko or Silken tofu with scallions and bonito flakes you sprinkle them on with soy sauce and ginger.

Mixed with a little soy sauce they become okaka, a classic filling for Onigiri. Dried and mixed with sesame and nori they make Furikake.

Substitutes and allergens

Bonito flakes are fish and off limits for people with a fish allergy. As a substitute in dashi, use dashi powder as the package says or, for a fish-free broth, dried shiitake with kombu. As a topping, crumbled toasted nori brings a sea aroma, but no smoke. A few drops of liquid smoke would distort the flavor; leave them out.

Buying and storing

Bonito flakes are sold at Asian grocery stores with a Japanese range and online, mostly in bags of 20 to 500 g. You find small portion bags on the same shelf. Good flakes are light pink-brown, large and smell strongly of smoke. If you buy for the first time, take a small bag so nothing goes stale. Gray, small crumbs taste flat.

Unopened, bonito flakes keep a long time; the date is on the package. After opening, press the air out of the bag, close it tightly and store it cool, best in the refrigerator or freezer. They taste best within two to three weeks. If they smell rancid, throw them away.