Wasabi: you know it well, or so you think. Chances are, however, 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. Even in Japan, the demand for real wasabi is so high that you'll often find the horseradish mixture instead, with little, if any, real wasabi mixed in.