Wasabi is used as a condiment traditionally served with raw fish (sushi and sashimi) and noodle (soba) dishes in Japan. The ground root-like rhizome pungently flavors many foods in Japanese cuisine and its bright green color adds color contrast, for which Japanese dishes are famous. In the last twenty years, because of low supply of fresh Wasabi rhizomes, substitutes made of mixtures of horseradish, mustard and food coloring have taken the place of freshly prepared Wasabi. Other parts of the Wasabi plant are also used. The leaves and petioles are picked or can be powdered for use as Wasabi flavoring, used now in many foods.

In traditional Japanese cuisine, Wasabi is prepared by grating the fresh rhizome against a rough surface. Some Japanese Sushi Chefs will only use a sharkskin grater. The sharkskin gives grated Wasabi a smooth, soft and aromatic finish.

Many believe that the Wasabi rhizome should be carefully peeled first before grating. It is recommended in either case to scrub the Wasabi rhizome with a soft brush before grating.

It takes eighteen months to two years for wasabi plants to produce an edible rhizome about 6 inches long and several offshoots for re-planting.