Wasabi

Wasabi is the enlarged stem of an East Asian cabbage relative that also accumulates sinigrin as a chemical defense. Wasabia japonica is a native of Japan and Sakhalin Island, where it grows alongside cool mountain streams. Wasabi is now cultivated in several countries and is occasionally available fresh in the West; whole and partly used roots keep for several weeks in the refrigerator.

Most wasabi served in restaurants is in fact ordinary dried horseradish powder, colored green and reconstituted with water. It has a similar pungency, but little else in common with true wasabi. When the fresh stem is grated a few minutes before the meal, it releases more than 20 enzyme-generated volatiles, some pungent, some oniony, some green, some even sweet.