Japanese Onion Koji Dressing (Wafu Dressing)

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Japanese Onion Koji Dressing (Wafu Dressing)

A velvety, umami-rich Japanese wafu dressing made with sweet onions, shoyu koji, and amakoji. Naturally probiotic, free of refined sugar, and packed with gut-healthy enzymes.

Prep Time5

Resting Time20

Total Time25

Course: dressing

Cuisine: Japanese

Keyword: healthy salad dressing, Japanese onion dressing, probiotic dressing, shoyu koji dressing, wafu dressing

Servings: oz

Calories: 73kcal

Equipment

High-speed blender or food processor

Ingredients

150 g Sweet onion (approx. ½ large, roughly chopped)
105 g Shoyu koji
50 g Amakoji (sweet rice koji paste)
90 g Rice vinegar (or apple cider vinegar)
100 g Taihaku sesame oil (unroasted sesame oil)
1 g Fine sea salt (2 pinches)

US Customary - Metric

Instructions

Combine the Base: In a high-speed blender or food processor, combine the chopped sweet onion, shoyu koji, amakoji, rice vinegar, and fine sea salt. Puree on medium-high speed until completely smooth.
Rest & Mellow (Crucial Step): Turn off the blender and let the puree rest undisturbed inside the blender container for 15 minutes. (This allows the vinegar and acidic koji paste to break down raw onion sulfur compounds, removing the harsh raw onion burn.)
Emulsify: Set the blender to medium-low speed. With the motor running, slowly stream in the Taihaku sesame oil in a steady drizzle until fully blended into a smooth, creamy emulsion.
Jar & Chill: Pour the dressing into a clean 16 oz glass jar, seal tightly, and store in the refrigerator.

Notes

Amakoji Substitutions: If amakoji is unavailable, substitute with 20g–30g of agave syrup, raw honey, or organic cane sugar. Avoid using raw mirin as a substitute, as its uncooked alcohol content creates a harsh bite in cold dressings.
Oil Choice: Taihaku sesame oil is cold-pressed and unroasted, providing a silky texture without heavy roasted notes. Light neutral oils like grape seed or rice bran oil make great substitutes.
Onion Variety: Sweet onions (Vidalia, Walla Walla) yield the mildest flavor. If using standard yellow onions, do not skip the 15-minute resting step.
Storage: Keep refrigerated in an airtight glass jar for up to 3 to 4 weeks. Shake well before each use. Flavors peak after 24–48 hours as the onion further mellows.

Nutrition