Wasabi is a member of the Brassicaceae family, which includes cabbages, horseradish, and mustard. Known as "Japanese horseradish", its root is used as a spice and has an extremely strong flavor. Its hotness is more akin to that of a hot mustard rather than the capsaicin in a chili pepper, producing vapors that stimulate the nasal passages more than the tongue. The plant grows naturally along stream beds in mountain river valleys in Japan. There are also other species used, such as W. koreana, and W. tetsuigi. The two main cultivars in the marketplace are W. japonica cv. 'Daruma' and cv. 'Mazuma', but there are many others.
Food features:Wasabi is generally sold either in the form of a root which must be very finely grated before use, or as a ready-to-use paste (either real wasabi or a mixture of horseradish, mustard, and food coloring), usually in tubes approximately the size and shape of travel toothpaste tubes.
Place of origin:In North America, a handful of companies and small farmers are successfully pursuing the trend by cultivating Wasabia japonica. While only the Pacific Northwest and parts of the Blue Ridge Mountains provide the right balance of climate and water for natural cultivation of sawa (water grown) wasabi, the use of hydroponics and greenhouses has extended the range.
Dietotherapy function:Wasabi is often served with sushi or sashimi, usually accompanied with soy sauce. The two are sometimes mixed to form a single dipping sauce known as Wasabi-joyu. Due to the expense and difficulty of cultivating wasabi, a very widely used substitute (imitation wasabi) is a mixture of (western) horseradish, mustard, and green food coloring; in American sushi restaurants this is generally referred to as "wasabi", while genuine wasabi, which is rarely available, is referred to as "fresh wasabi". Similarly, when wasabi is sold in tubes, the contents may be genuine wasabi, horseradish, mustard, and green food coloring, or a mixture of these. In Japan, horseradish is referred to as seiyō wasabi (西洋わさび?, "western wasabi").