What's the Deal with Fake Wasabi?

Besides being neon-hued and sinus clearing-hot, what exactly is that bright green blob served alongside sashimi? If you’re putting it into your soy sauce Stateside, chances are it’s a mix of horseradish powder, mustard and green food coloring (yellow dye no. 5 and blue dye no. 1, for those keeping track), and not actual wasabi. In fact, about 99 percent of wasabi served in American restaurants and 95 percent served in Japanese restaurants...