The pungent green wasabi is native to Japan, as its botanical name Eutrema japonicum indicates.
A member of the brassicae family, it grows wild along the banks of mountain rivers and streams throughout the country. There are written records of it as far back as the Asuka Period (592-645), though it was used for medicinal purposes rather than food until the 13th century. A cookbook published in 1489 recommends using grated wasabi mixed with vinegar to accompany carp sashimi. (The part of the wasabi plant that’s grated is not the root — it’s actually the rhizome.)
Wasabi was first seriously cultivated in the early 1700s in the Utougi region, which is now part of Shizuoka City, Shizuoka Prefecture. Some of this wasabi was presented to Tokugawa Ieyasu, the first Tokugawa shogun, who fell in love with its refreshing pungency. The kidney-shaped leaves of the wasabi plant also resemble those of the aoi (asarum) plant, which make up the Tokugawa family crest.
This was considered significant, so wasabi was promptly placed under the direct protection of the shogunate, with its cultivation restricted to Utougi.
Shizuoka Prefecture remains one of the major producers of wasabi to this day.
Wasabi remained an expensive and rare product until around the 1810s, when the citizens of Edo (now Tokyo) started growing it for their own consumption. Grated wasabi soon became a popular addition to cold soba noodles, cold tofu and the newfangled type of sushi of raw fish slices served on vinegared rice — not only for its flavor, but for its reputation in preventing digestive problems associated with food poisoning. Modern research has shown that the people of 19th-century Edo may have been on to something; the isothiocyanates that are produced when wasabi cells are broken up help to inhibit microbial growth.
Most commercially grown wasabi is processed for use in wasabi pastes or powders, usually mixed with white horseradish, which is a lot less demanding to grow. It’s hard for individual consumers to get fresh wasabi rhizomes outside of Japan, but here it’s readily available at most supermarkets.
Fresh wasabi is quite expensive, but has a far superior flavor and fragrance to ready-made pastes or powders. The fibers of the wasabi rhizome need to be broken down for the isothiocyanates, which are the source of that unique pungency, to develop, so it’s best to use a very fine grater for the best flavor.
Although wasabi rhizomes are available year-round, a special treat in spring is ha-wasabi, the crispy new leaves. The fibers of ha-wasabi also need to be broken down to create a pungent flavor. To do this, briefly boil the leaves with their stems, then plunge them in cold water and squeeze out. Rub some salt into them or cover with soy sauce and refrigerate in a closed container for a day before using in salads, side dishes etc.
This month’s recipe uses grated wasabi to add a subtle pungency to a beef and broccoli dish.
Recipe: Steak and broccoli with wasabi sauce
150 grams beef for steak (sirloin or rump) at least 1 cm thick
1 stalk broccoli or nanohana
2 teaspoons vegetable oil
2 teaspoons soy sauce
2 tablespoons sake
a pinch of sugar (optional)
1 tablespoon freshly grated wasabi
Take the steak out of the refrigerator 30 minutes before cooking.
Cut the broccoli into small florets. Boil for 2-3 minutes until crisp-tender. Drain and immediately plunge into cold water. Drain again.
Lightly sprinkle the steak with salt and pepper. Heat up the oil on a frying pan and sear the steak on one side. Turn it over and brown on the other side. Two minutes before it’s done, add the soy sauce, sugar and 1 tablespoon of sake, and spread the wasabi on both sides.
Cook the steak to your liking, then take out of the pan, wrap in aluminium foil and leave to rest for 5 minutes.
Add the broccoli and remaining sake to the pan. Slice the steak. Serve it with the broccoli and pan juices, with plain rice or on its own with drinks. Top with grated wasabi to taste.