Wasabi is most familiar as the tearfully pungent green paste that accompanies sushi. However, it is more versatile than that, and in the recipe that follows, it is combined with asparagus (or green beans).
Some Japanese cookbooks give the impression that the 4-to-5-inch wasabi root, which is indigenous to swampy earth next to cold mountain streams in Japan, is sometimes available fresh in this country. Maybe so, but Japanese produce dealers in California claim they don't carry it and, according to the U.S. Department of Agriculture, fresh wasabi is not allowed in the United States, with the exception of Hawaii.
It's also not grown with any success outside of Japan. It's a shame since the freshly grated root has a compelling herbal fragrance that is missing in the dried and powdered product that is popularly used. Even in Japan the powdered form is more readily purchased than the fresh, which is easily acquired though expensive.
The fresh root, if it can be gotten -- in Japan it's sold in water-filled tubs -- should be pared and then rubbed on a fine grater just before using.
Powdered wasabi comes in tins of various sizes in Japanese markets. Like ground mustard, this light green powder should be mixed half and half with tepid water and allowed to sit at least 10 minutes to develop its flavor. A little lump of this paste traditionally accompanies sushi, and should be mixed with a little soy sauce to make a dip. Unless you go through a lot of it, buy wasabi in small quantities. As with any spice, once opened it deteriorates over time. Some American chefs have begun to experiment with wasabi, mostly using it as a base for a dipping sauce for grilled meat and fish.
Wasabi paste is available in 1.2 ounce tubes, but convenience is about all the paste has going for it. It lacks the bite of the freshly mixed powder especially when it sits in the refrigerator after it has been opened.
ASPARAGUS (or Green Beans) WITH WASABI-MISO DRESSING (6 servings)
2 teaspoons wasabi powder
2 teaspoons water
1 pound thin asparagus (or green beans)
1 egg yolk
2 teaspoons white miso (available in Japanese markets)
2 teaspoons Japanese soy sauce
1 tablespoon lemon juice
1 tablespoon rice vinegar
2 tablespoons minced scallions
Mix the wasabi powder and water together to make a thin paste; allow to sit for 15 minutes.
Cut asparagus on the bias into oblong pieces about 1-inch in length. Cook in boiling water until barely tender, 1 1/2 minutes or so; Drain and set aside.
Mix egg yolk with the wasabi vigorously, then toss with asparagus and the rest of the ingredients, and serve.