- 1 small sweet onion, coarsely chopped
- 5 tablespoons plus 1 teaspoon Japanese soy sauce
- 1/4 cup plus 2 teaspoons rice vinegar
- 4 teaspoons water
- 1 teaspoon sugar
- 1 pinch fine sea salt
- 1/2 teaspoon dry mustard
- 1 pinch freshly ground pepper
- 2 tablespoons plus 2 teaspoons grapeseed oil
- 2 tablespoons plus 2 teaspoons toasted sesame oil
- Pulse onion in a food processor until finely chopped. Transfer to a fine sieve set over a small bowl and let drain.
- Place 3 tablespoons drained onion, soy sauce, vinegar, water, sugar, salt, mustard, and pepper in a bowl and whisk until sugar and salt are dissolved and mixture is combined. Whisk in oils until combined.
Adapted from Nobu: The Cookbook, by Nobuyuki Matsuhisa (Kodansha U.S.A., 2001)