You’ve never actually eaten real wasabi, or at least not very often.
This is because most of the wasabi served outside of Japan is a mixture of horseradish, mustard and food coloring.
Most of the wasabi you’ll find in Japanese restaurants in the United States and even often in Japan is not real wasabi.
Real wasabi comes from grating the root Wasabia Japonica (originated in Japan). For the freshest wasabi, you must grate the root right before serving, as the wasabi will only hold its strong flavor for about 15 minutes after preparation. – Tiny Fox Lab
Preview photo credit: MIURA, Yuji / wikipedia