Japanese Mashed Potato Salad with Carrots

Making Authentic Japanese Mashed Potato Salad

I remember the first time I had this at a tiny izakaya in Tokyo. It wasn't the gloppy, heavy stuff you find at a deli. It had these distinct bits of crunch and a sharp, vinegary hit that cut right through the creamy mayo. I spent a few weekends trying to recreate that specific balance at home.

The real win here is the texture. You don't want a smooth puree. You want a rustic mash where some chunks of potato still exist to hold onto the dressing. It's a hearty, fresh side that feels lighter than Western versions because of the acidity.

If you're looking for a quick win in the kitchen, this is it. You can have the whole thing ready in 40 minutes, and it actually tastes better after it sits in the fridge for an hour. This Japanese Mashed Potato Salad is essentially the ultimate comfort food for people who like a bit of zing.

Why This Texture Works

• Hot Acid: Stirring rice vinegar into steaming potatoes allows the acid to penetrate the starch deeply before it cools.
• Partial Mashing: Leaving small lumps creates a varied mouthfeel that prevents the salad from feeling like baby food.
• Water Removal: Salting the cucumbers draws out excess moisture, so the dressing stays thick and doesn't turn watery.

What Each Ingredient Does

The Ingredient List

• 1.1 lbs (500g) Yukon Gold or Russet potatoes, peeled and cubed Why this? Yukon Golds stay creamy but hold their shape.
• 1 tsp (6g) salt
• 1 tbsp (15ml) rice vinegar Why this? Provides a mild, sweet acidity.
• ½ tsp (3g) granulated sugar
• 2 medium (100g) carrots, finely diced
• 1 medium (100g) cucumber, thinly sliced and salted
• 2 large (100g) hard boiled eggs, chopped
• 3 oz (85g) cooked ham, diced
• 2 stalks (10g) scallions, thinly sliced
• ½ cup (110g) Kewpie mayonnaise Why this? Made with only egg yolks for a richer taste.
• ¼ tsp (1g) ground black pepper
• ½ tsp (3g) salt

Essential Kitchen Tools

You don't need a fancy food processor for this. A standard pot for boiling and a large mixing bowl are the main requirements. I prefer using a hand masher or even just a sturdy fork to keep the texture rustic.

A paper towel is actually a critical tool here for squeezing the cucumbers. If you skip the squeezing part, you'll end up with a puddle at the bottom of your bowl.

Step by step Process

Phase 1: The Warm Mash

1. Place cubed potatoes in a pot of cold salted water. Bring to a boil and simmer for 15–20 minutes until fork tender.
2. Drain thoroughly. While the potatoes are still hot, return them to the pot and mash them with a masher or fork, leaving some small lumps.
3. Immediately stir in the rice vinegar and sugar. Let the potatoes cool slightly so the vinegar can soak in.

Phase 2: Prepping the Texture

4. Toss sliced cucumbers with a pinch of salt and let sit for 5 minutes. Squeeze out the excess water using a paper towel.
5. Blanch the diced carrots in boiling water for 2 minutes until softened but still snappy, then drain.
6. Roughly chop the hard boiled eggs and ham.

Phase 3: The Final Fold

7. In a large mixing bowl, combine the cooled mashed potatoes, cucumbers, carrots, eggs, ham, and scallions.
8. Add the Kewpie mayonnaise, black pepper, and salt, then fold together until combined.

Chef's Note: Don't over mix once the mayo goes in. Fold it gently so you don't break the egg yolks too much, which keeps the salad looking clean.

Troubleshooting Common Issues

Easy Ingredient Swaps

If you don't have Kewpie, you can use regular mayonnaise, but add a pinch of sugar and a drop of soy sauce to mimic that savory depth. For those who want a different vibe, you can swap the ham for canned tuna or even smoked salmon.

If you're looking for a more traditional Western style, you might prefer my Potato Salad for 6 recipe, which uses a different base of dressing.

Quick Adjustment Guide

• Want more crunch? Add finely diced celery.
• Want it creamier? Add an extra tablespoon of Kewpie.
• Want more tang? Increase rice vinegar by 1 teaspoon.

Adjusting the Batch Size

When scaling this recipe down to a half batch, use a smaller pot for the potatoes so they don't dry out. I recommend beating one egg in a bowl and using half of it to keep the proportions right.

For doubling or tripling the recipe, don't just triple the salt and pepper. Increase the seasonings to about 1.5x and taste as you go. Work in a very large bowl; if you crowd the ingredients, you'll end up over mixing the potatoes while trying to incorporate the mayo, which ruins the texture.

Kitchen Myths

Some people think you need to peel the potatoes for this recipe. While it's traditional, leaving the skins on adds a nice earthiness and extra nutrients. It just changes the look from a pale cream to a speckled rustic mash.

Another myth is that you must use a specific "potato salad" potato. Any waxy potato works. If you only have Russets, just be extra careful not to over mash them, as they fall apart much faster than Yukon Golds.

Storage and Waste Tips

Store your Japanese Mashed Potato Salad in an airtight container in the fridge for up to 3 days. It doesn't freeze well because the mayonnaise will separate and the cucumbers will lose their snap.

To avoid waste, save your potato peels. Toss them in olive oil and salt, then bake at 400°F (200°C) for 15 minutes for a quick snack. If you have leftover hard boiled eggs, chop them into a morning toast topping.

Perfect Side Pairings

This salad is heavy on cream and acidity, so it pairs well with grilled proteins or fried foods. I love serving it alongside a piece of salty grilled mackerel or a crispy chicken katsu.

If you want another creamy option to serve on a platter, try a traditional egg potato salad for a more classic feel. The contrast between the two styles of potato salad makes for a great spread at a potluck.

For a complete meal, add a side of steamed broccoli or a simple cabbage slaw. The freshness of the raw cabbage complements the rich, savory notes of the Kewpie mayo.