Wasabi Is Rarely Real in Restaurants

That potent, sinus-clearing green paste served alongside your sushi is almost certainly not what you think it is. The vast majority of the time, what is labeled "wasabi" is actually a clever imitation made from European horseradish that has been ground into a powder, mixed with mustard extract, and dyed green. This common substitution is a matter of pure economics and agricultural reality. True wasabi, derived from the rhizome of the *Wasabia japonica* plant, is one of the most difficult and expensive plants in the world to farm commercially.

The authentic wasabi plant is semi-aquatic and notoriously finicky, requiring a constant supply of cool, clean running water and plenty of shade, conditions typically found only in the mountain stream beds of Japan. This difficulty drives up the cost significantly. The sharp heat in both horseradish and real wasabi comes from the same group of chemical compounds, called isothiocyanates. However, the experience is quite different. The imitation provides a blunt, powerful heat that rushes up the nose, while freshly grated wasabi has a more complex, herbaceous, and slightly sweet flavor profile, with a clean heat that dissipates quickly.

Because the volatile compounds in real wasabi lose their pungency within about 15 minutes of being grated, it is traditionally prepared fresh at the table, often on a special grater with a rough surface like sharkskin. The paste form is a giveaway that you're likely eating the horseradish-based alternative. While the stand-in delivers the familiar kick, it lacks the delicate and fleeting botanical notes that make its authentic counterpart a true culinary delicacy.