Tosazu is a fishy take on the standard sanbaizu sunomono dressing, and includes smokey katsuobushi.

Tosazu means Tosa-style vinegar (su). Tosa is the old name for what is known today as Kochi prefecture, on the island of Shikoku, Japan. The area is famous for its katsuobushi (skipjack tuna flakes), the star ingredient of this recipe. Kochi (new Tosa) produces other katsuobushi-centered products as well. For example, Kochi dwellers dip their sushi in tosashoyu (i.e. Tosa-style soy sauce), which contains dashi made with katsuobushi.

Tosazu is basically a fishier, smokier version of sanbaizu, a typical sunomono (vinegared dish) dressing. This fishy taste also lends itself well to namasu recipes, such as our kouhaku namasu. Try it out, or feel free to experiment with the dish of your choice. Let us know how you like to use tosazu in the comments below!

5 from 1 vote


Servings 4
Cook Time 8 minutes
Total Time 8 minutes


  • ½ cup sanbaizu
  • 1 tbsp mirin
  • 3 g katsuobushi ½ cup


  • Put the sanbaizu and mirin in a pot and bring to a boil.
  • Add the katsuobushi flakes and turn off the heat.
    Tosazu - Step2
  • Let it sit a little, then strain in a cheesecloth. Aaaand that’s it!

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