An exuberantly hot 'green horseradish' powder essential to sashimi, which is not actually a horseradish at all. This unique Japanese spice once grew naturally alongside clear mountain streams, but today it is mainly cultivated. The wasabi root is peeled, then grated and used as a condiment for sushi, sashimi and chilled soba noodles. These days the fresh root is something of a luxury; most people use ready-to-use grated wasabi paste.
