Note: Monosodium glutamate is essential to the flavor of Japanese mayonnaise. It can be purchased from most Asian grocers under the Aji-No-Moto brand, in American supermarkets under the brand name Ac'cent, or online. Hondashi can be found in Japanese markets or ordered online.
- 2 tablespoons rice vinegar
- 1 tablespoon plus 1 teaspoon malt vinegar
- 1 teaspoon Kosher salt
- 1/2 teaspoon MSG powder (see note)
- 1/2 teaspoon Japanese mustard powder
- 1/8 teaspoon hon-dashi powder (see note)
- 1/8 teaspoon garlic powder
- 2 large egg yolks
- 1 cup vegetable oil
In a small bowl, whisk together rice vinegar, malt vinegar, salt, MSG, mustard powder, hon-dashi powder, and garlic powder until hon-dashi is completely dissolved.
Place vinegar mixture in the workbowl of a food processor fitted with a steel blade along with the egg yolks. Pulse to combine.
With the motor running, slowly drizzle in vegetable oil in a thin, steady stream. Transfer mayonnaise to an airtight container and store in refrigerator for up to two weeks.