What's Really In That Green Paste You Call Wasabi?

Are you really eating wasabi with your sushi, or is that just a load of horseradish? Discover the truth behind this rare Japanese rhizome, and get recipes.

Sushi with Soy Sauce, Pickled Ginger, and Wasabi
Photo by Meredith.

Oh, you know wasabi. It's that green stuff that blows your hair back and scours your sinuses when you eat it with your sushi. Or is it?

You've probably guessed by now that I'm not going to say yes, it's wasabi. End of story. Move along.

The truth is, real Wasabia japonica (aka Japanese horseradish) is rare and expensive even in Japan and is not necessarily served with your everyday sushi in the United States. They are a rhizome, which is a modified subterranean plant with a stem that sends out roots and shoots from its nodes. What you've been eating is regular ol' horseradish.

Horseradish (Armoracia rusticana) is in the same Brassicaceae family as wasabi; a family, by the way, that includes cabbage, broccoli, cauliflower, radish, mustard, and watercress. But while they share the same fiery personality, the two cousins have their differences.

Wasabi and Horseradish
Photos by Meredith.

What's the Difference Between Wasabi and Horseradish?

Wasabi vs Horseradish
Wasabi vs Horseradish.

So, What's in the Green Stuff We're Calling Wasabi?

The tube of paste or package of powder you can buy usually gets its heat from horseradish and its color from food dye. There may be other ingredients in the mix — you'll have to read the labels — and there might actually be some wasabi powder down towards the bottom of the list.

What brought all this on? Well, I was shopping at Uwajimaya in Seattle's International District, and I happened to see a sign for "Fresh Wasabi Root." The price was an eye-watering $99.99 per pound. So, you know, sold!

Fresh Wasabi
Photo by Vanessa.

I asked the produce manager how to prepare it, and he said I should just grate it. But I'd always thought it was paste-like when I ate it with sushi, so I figured he must be leaving out some steps. I bought it along with a tube of wasabi paste and a can of wasabi powder, thinking I'd do a simple side-by-side comparison back at the Allrecipes kitchen.

But after researching wasabi online, the story took a different turn. Instead, it was all about what real wasabi was and wasn't.

Wasabi Paste, Wasabi Powder, Wasabi Root Grated with Microplane
Photo by Vanessa Greaves.

But I still did a taste test with several folks here at Allrecipes. The results:

  • The "wasabi" in the tube had a sustained, nose-clearing heat with a salty aftertaste and a long ingredient list that included wasabi powder in the third from the bottom position. And the last ingredient was a mix of food colorings.
  • The powdered "wasabi" in a can, mixed into a paste with water, was hot but bland. It had three ingredients, none of which was wasabi. It got its color from spirulina.
  • And the real-damn-deal wasabi? The produce manager was right...All I had to do was grate it. Everyone expected it to blow their heads off, but it didn't. Don't get me wrong, it had plenty of sharp heat. But it was actually milder and more complex than either of the two wasabi wannabes, with a green, vegetal flavor right there along with the bite.

How to Prepare Fresh Wasabi

Let's say you find it by chance as I did in an Asian specialty food market.

  • Scrub the wasabi and peel away the outer layer with a knife or vegetable peeler. Note: peel only the portion you'll use right away.
  • Slice a bit off the bottom of the rhizome to expose a fresh surface.
  • Rub the end on a ceramic grater or Microplane grater until you get a pile of wasabi. If you want to get totally traditional, use a sharkskin grater like they do in Japan.
  • Let it sit for a couple of minutes, then press it into a little heap and serve it or use it in a recipe right away; it loses its potency after about 15 minutes.
  • The leaves and leaf stems are edible, too. Packing a sharp mustardy flavor, they're used in salads or stir-frys.
  • To store leftover wasabi, wrap it in a wet paper towel and keep it in the fridge for up to two weeks.
Wasabi Root and Ceramic Grater
Photo by Vanessa Greaves.

Recipes With Wasabi

Now that you know what may or may not be in a container of prepared "wasabi," try to find one with real wasabi towards the top of the list of ingredients. Here are a few ideas for using wasabi in recipes:


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