Most people don't think of Japan when they think of potato salad, especially here in the South. However, potato salad is a popular, though non-traditional summertime dish in Japan. This version is mild and creamy, without the acidic tang that American or German potato salads have. The key ingredient is the mayonnaise. I've served this potato salad to several "born & bred" Southerners, all of whom were skeptical at first. The response has always been overwhelmingly positive.
Kewpie mayonnaise is THE mayonnaise brand in Japan. Made from only egg yolks as opposed to the entire egg, the secret to its incredible flavor is the vinegar. Using only egg yolks is also what gives Kewpie its color; it has a much more yellow hue than most mayonnaises. Kewpie uses a rice vinegar, which gives the mayonnaise a unique taste. Mayonnaise is an extremely popular condiment in Japan, showing up on top of pizzas, hot dogs and okonomiyaki. Even here in America, it's the basis of most sushi restaurants' "secret" Volcano or Dynamite sauces (just a mixture of Kewpie mayonnaise, Sriracha and occasionally Thai sweet chili sauce). I particularly enjoy Kewpie mayonnaise on fries, specifically Chick-Fil-A's waffle fries (note: Chick-Fil-A has VERY good mayonnaise as well).
You can find Kewpie mayonnaise is most Asian markets; I have also seen it at Cost Plus World Market as well as Whole Foods. I've read online that, in a pinch, you can add rice vinegar and MSG to regular mayonnaise to recreate the flavor of Kewpie; I've never tried this, though, so I can't vouch as to how well it works.
Japanese Potato Salad
adapted from my mom & Just Hungry
4 Yukon Gold potatoes, peeled & cut into chunks
2 carrots, peeled & cut into chunks
1 small white onion, thinly sliced
2 eggs, hard-boiled
Salt & pepper
3/4 - 1 cup Kewpie mayonnaise
Bring a pot of water to a boil; salt the water and add the potato and carrot chunks. Boil until tender, about 15-20 minutes. Meanwhile, using a mandoline, thinly slice the cucumber. Combine in a bowl with the sliced onion. Sprinkle with salt and let sit 10 minutes to draw out the excess moisture. Tightly squeezed the excess moisture from the slices and set aside.
Drain potatoes and carrots; lightly season with salt and pepper. Let cool to room temperature, then add the cucumber and onion slices.
Finely chop the hard-boiled eggs and add to the potato mixture. Mix in the mayonnaise and season to taste. Cover and chill for several hours before serving.
Taste the potato salad before serving - some of the mayonnaise may have been absorbed. Add more mayonnaise if desired.