When enjoying sushi or sashimi, the sharp green paste on the side of your plate is often called “wasabi.” But is it really wasabi? Many people are surprised to learn that what we usually eat is not genuine wasabi at all. Instead, it’s often horseradish or mustard, two very different plants with their own histories and culinary uses. Let’s explore the origins, differences, and roles of real wasabi, horseradish, and mustard in Japanese and global cuisine.
Mustard: Ancient Origins in China
The story begins in China. Mustard, known in Chinese as jie mo (芥末), can be traced back as early as the Zhou Dynasty. It is made by grinding the seeds of the mustard plant (Brassica juncea) into a fine powder. The resulting condiment, yellow in color, is sharp, pungent, and affordable.
This “yellow mustard” spread around the world and became especially popular in Europe and North America. Today, it’s the same mustard you find on hot dogs at IKEA or American ballparks. While inexpensive, it plays an important role as one of the earliest pungent condiments in human history.
Wasabi: Japan’s Precious Green Gold
The “wasabi” used in Japanese cuisine is something else entirely. Real wasabi comes from the rhizome of the Wasabia japonica plant, native to Japan. Unlike mustard, wasabi grows only in very clean, cold, running water and requires three years of cultivation before harvesting, which makes it extremely rare and expensive.
The earliest record of wasabi dates back to 685 AD, discovered on wooden tablets unearthed in Asuka village, Nara Prefecture. Originally used for medicinal purposes, wasabi became a culinary treasure during the Heian and Kamakura periods, especially valued for its antibacterial properties, which pair well with raw fish dishes like sushi and sashimi.
Freshly grated wasabi root has a unique, fleeting pungency. Its spiciness is sharp yet quickly dissipates, unlike chili peppers. Because of its high cost, genuine wasabi is usually served only at high-end sushi restaurants in Japan.
Horseradish: The Affordable Substitute
So what about the green paste served at most sushi restaurants worldwide? The truth is, in over 90% of cases, it isn’t real wasabi—it’s horseradish.
Horseradish (Armoracia rusticana) is a plant native to Europe and western Asia, also known as “Western wasabi.” Its thick, white root has a powerful, spicy flavor similar to wasabi but far cheaper to produce. Horseradish has been cultivated in China since it was introduced from Britain more than 80 years ago, now grown widely in Shanghai, Shandong, and Liaoning.
Because horseradish is naturally pale yellow, manufacturers add green food coloring to make it resemble real wasabi. The result is the familiar “wasabi paste” that comes in tubes or packets at sushi restaurants, especially conveyor-belt sushi chains. While not authentic, horseradish paste still delivers a sharp, sinus-clearing kick that complements sushi and sashimi by cutting through the richness of raw fish and neutralizing fishy odors.
Mustard vs. Wasabi vs. Horseradish: Key Differences
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Mustard (yellow or brown): Originated in China, made from mustard seeds, often used in sauces, pickles, and Western hot dogs.
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Wasabi (true wasabi): Grown in Japan, from the rhizome of Wasabia japonica, rare and expensive, freshly grated for premium sushi and sashimi.
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Horseradish (green “wasabi” substitute): European origin, cheap, pungent, often colored green, and widely used as a wasabi alternative in everyday sushi restaurants.
Culinary Roles in Japanese Cuisine
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Sushi and sashimi: Wasabi (or horseradish paste) is traditionally served with raw fish to enhance flavor, add spiciness, and kill bacteria.
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Soy sauce pairing: Mixing a small amount of wasabi into soy sauce creates a dip that balances the richness of fatty fish like tuna or salmon.
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Other uses: Mustard and horseradish also appear in salad dressings, grilled meats, and pickled dishes across various cuisines worldwide.
Final Thoughts
Next time you enjoy sushi or sashimi, take a closer look at the green paste on your plate. Is it real wasabi, horseradish, or mustard? Each has a fascinating history—from mustard’s ancient Chinese roots, to wasabi’s prized role in Japanese fine dining, to horseradish’s place as a clever and affordable substitute.
Whether authentic or imitation, these condiments highlight the ingenuity of global cuisine and how flavor traditions adapt across cultures.
Chefco supplies a wide range of Japanese restaurant essentials—from sushi knives and sashimi prep tools to storage equipment and condiments. Partnering with Toronto’s local restaurants, we bring authentic flavors and professional kitchen equipment to your table.
