Wasabi is the root of the Eutrema wasabi plant. It is also called the Japanese horseradish but there is not actually connection. In Japan the root is available fresh and is often grated and added to fish dishes. Powdered wasabi that has been prepared in a paste is available worldwide.

In its dry powdered form it has little taste and only develops its eye tearing pungency when mixed with water. It loses its flavour when exposed to heat, so is typically served with and added to cold foods. It is essential to sashimi and sushi. The powdered version has a shelf life of several months, and the prepared paste will last almost as long if properly stored.