Wafu Onion Dressing (Japanese Grated Onion Dressing)
A bright, savory-sweet Japanese-style dressing built on freshly grated onion, soy sauce, rice vinegar, and mirin, finished with toasted sesame oil. Resting mellows the onion's bite, and the result is perfect over simple green salads, tofu, grilled chicken, or seared steak.
- Prep
- 12 min
- Cook
- 2 min
- Wait
- 45 min
- Total
- 59 min
- Makes
- About 1½ cups (360 ml), enough for 8 servings of 3 tablespoons
Steps
Before you start
- Plan for about 1 hour total: the dressing needs 15 minutes to cool and 30 minutes to rest so the onion flavor mellows.
- Use a fine grater (microplane or the small holes of a box grater) so the onion turns to a wet pulp rather than shreds.
- Have a clean 2-cup (500 ml) jar with a tight lid ready for mixing and storing.
- Open a window or run a fan if raw onion bothers your eyes; chilling the onion for 15 minutes beforehand also helps.
Grate the onion
- Peel the onion and trim the root end, leaving enough root to hold while grating.
- Grate the onion on a microplane or the small holes of a box grater over a medium bowl or the jar, catching all the juice.
- Stop when you have about ½ cup (about 120 g) of wet pulp; discard the tough root nub.
- If using garlic, grate it into the same bowl.
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Ready when: Onion looks like a wet, fine pulp with no large shreds.
Tip: Grate the onion straight into the bowl so no juice is lost; the juice carries much of the flavor.
Warm the sweet base
- In a small saucepan, combine the soy sauce, mirin, and sugar.
- Warm over medium-low heat, stirring, until the mixture just begins to bubble gently around the edges, then keep it at a gentle simmer for 1 minute.
- This dissolves the sugar and cooks off the raw alcohol taste of the mirin.
- Remove from the heat.
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Ready when: Sugar is fully dissolved and no granules are visible when you stir; small bubbles break at the surface.
Tip: Don't boil hard; the soy sauce will reduce and turn too salty.
Cool the base
- Let the soy mixture sit in the saucepan, off the heat, until it is room temperature or just barely warm to the touch, about 15 minutes.
- Adding it hot would cook the onion and dull its fresh flavor.
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Ready when: A drop on your wrist feels neutral, not warm.
Tip: To speed it up, pour the mixture into a shallow bowl.
Combine with vinegar
- Pour the cooled soy mixture over the grated onion.
- Add the rice vinegar and stir with a whisk or fork for 15 seconds to combine.
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Ready when: Onion pulp is evenly suspended in a uniform brown liquid.
Whisk in the oils
- Whisk in the neutral oil and toasted sesame oil, then stir in the sesame seeds.
- Whisk vigorously for 30 seconds, or screw the lid onto the jar and shake hard for 20 seconds, until the dressing looks slightly cloudy and the oil is broken into small droplets.
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Ready when: Dressing looks cloudy and lightly emulsified, with no large pools of oil on top.
Tip: Toasted sesame oil is strong; measure it exactly so it doesn't overpower the onion.
Rest and mellow
- Cover the jar and refrigerate for at least 30 minutes.
- During this time the onion softens in the vinegar, losing its sharp raw bite and flavoring the whole dressing.
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Ready when: Dressing smells savory and sweet rather than sharply of raw onion.
Taste and serve
- Shake or whisk the dressing well, since it separates as it sits.
- Taste on a lettuce leaf: if too salty, add 1 tsp rice vinegar or 1 tsp water; if too sharp, add ½ tsp sugar.
- Spoon about 3 tablespoons per serving over salad, tofu, grilled chicken, or sliced steak.
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Ready when: Balanced flavor: salty, tangy, and lightly sweet, with a nutty finish.
Tip: Dress salad right before serving so the greens stay crisp.
Good to know
Tips
- Grate rather than chop the onion; the fine pulp dissolves into the dressing and gives it body without needing a blender.
- For a smoother, thicker dressing, blend everything with an immersion blender for 15 seconds after step 5.
- Use hon-mirin (true mirin) if you can find it; it tastes rounder than 'mirin-style' seasoning, which may already contain added sugar.
- Try it as a marinade for chicken thighs or as a dipping sauce for shabu-shabu and gyoza.
Make ahead
"The dressing can be made up to 5 days ahead; its flavor deepens after a day. Shake well before using."
Storage & reheating
Room temperature: not recommended beyond 1 hour because it contains fresh onion. Refrigerator: up to 5 days in a sealed jar; it will separate, so shake well. Freezer: not recommended, as the texture breaks down. Serve cold or at room temperature; no reheating needed.
Substitutions
- mirin → 1 tbsp sugar plus 2 tbsp water or dry sake. Use ½ tbsp extra sugar with water if omitting alcohol entirely; skip the sugar in step 2 if you use this blend, as it is already sweet.
- unseasoned rice vinegar → apple cider vinegar. Slightly fruitier and sharper; use the same amount.
- Japanese soy sauce (koikuchi) → tamari or reduced-sodium soy sauce. Tamari makes it gluten-free (check the label); reduced-sodium gives a milder salt level.
- yellow onion → sweet onion such as Vidalia. Gives a milder, sweeter dressing; reduce sugar to 1 tsp.