The Small Shark Skin Oroshiki is the perfect grater for wasabi. Trusted and used for centuries by Japanese sushi, soba, and yaki chefs, with some modification in the material used (it's not actually shark, it's a manta ray species). These graters are carefully constructed by hand with hinoki cedar wooden handles by the Chojiro company in Gifu prefecture. Smaller oroshiki are meant for smaller sized wasabi stems (1/4 lb or smaller) and will not work with larger sized wasabi.
An oroshiki and a tawashi (brush) are must have tools when grating wasabi. The goal with grating wasabi is to create as much cellular destruction as possible thereby potentiating the pungency, sweetness and characteristic earthy wasabi flavor. Traditional shark skin oroshiki are an excellent, natural surface with the perfect grating texture. The surface feels like sand paper, will last you 100's of grinds, and can be used with other vegetables such as carrots, daikon, ginger, nagaimo, and garlic.
Traditional shark skin graters will grind a paste with a 'chunkier' texture. I've found this suspends the degradation of the wasabi pungency and flavors creating a longer lasting cream. There are newer, more complex oroshigane that will grind a finer cream, but this is an excellent tool rooted in history and used by most chefs today.
Chojiro is one of the most celebrated oroshiki producers in Japan. I personally visited their production facility and was impressed by their dedication and craftsmanship. They even let me make a little grater! The surface of this oroshiki is not shark. It's a type of manta ray species that is purchased as a by-product from South-East Asian fishing markets. The frictional bumps and bristles of this species, combined with hand made expertise create the perfect wasabi grating tool.
