|Wasabi, or Japanese horseradish, is nicknamed nami da (tears) in Japanese. This strong, aromatic spice with a definite "bite" and the ability to instantly clear the sinuses has become popular in the West in recent years.
Wasabi's fresh, stimulating flavor and its abundance of protein-digesting enzymes make it an ideal condiment with raw fish dishes such as sashimi and sushi. Japanese sushi connoisseurs use wasabi to complement the flavor of red-fleshed and oily fish, such as tuna, yellowtail, and salmon, that live close to the surface. Although wasabi can also be used with white-fleshed bottom fish such as snapper and grouper, grated ginger is often preferred with them.
A small amount of wasabi is mixed into the shoyu-seasoned dip that accompanies sashimi. In preparing sushi, wasabi is rubbed on bite-sized "fingers" of vinegared rice, then topped with raw fish. (See "How to Plan a Te-Maki Party" in the Recipes section of this web site.) Wasabi is also traditionally added to the broth or dipping sauce served with soba noodles.
In Japan, the pale green flesh of wasabi root is finely grated and used fresh. Unique to the islands of Japan, fresh wasabi roots are rare and expensive. Powdered wasabi, or a mixture of powdered horseradish, mustard and wasabi, is a convenient substitute for the fresh root. It keeps almost indefinitely if stored in a cool, dry place. Packaged in small tins or small plastic-lined foil envelopes, powdered wasabi is available in many natural food stores. However, most commercial "wasabi" actually contains no wasabi at all, and is artificially colored. When mixed with water to make a paste, this type of product is bright green, whereas natural wasabi powder is a dull greenish-gray.
Mix wasabi paste about 10 minutes before you begin eating. It is best to prepare only as much as you plan to use, because the flavor weakens over time. In a small cup or custard bowl mix a small amount of water with the wasabi powder to make a paste (about 1 part water to 2 parts powder). The paste should be thick, not runny. Cover the container, or turn it upside down on the counter and let it sit for 10 minutes to allow the flavor to heighten. (Exposure to air will cause it to lose some of its flavor.)