What is it?

Other than a very lewd-looking root vegetable (at least from this picture I took), the not-so-pretty yam is also known as a Chinese yam, yamaimo, Japanese mountain yam, or Korean yam. It can grow to up to three feet long and close to four pounds.

Ironically known in the U.S. as an invasive weed rather than an edible vegetable, it's starchy and bland and doesn't need to be cooked before eating.

How is it used?

In China, this vegetable is used more for medicinal purposes than for food, but in Japan it is a staple. Often eaten raw in Japanese food, the root is soaked whole in a water-and-vinegar mixture to detoxify oxalic acid that is present in the skin. When grated, it takes on a gelatinous quality.

Raw, grated nagaimo mixed with dashi, soy sauce and mirin is a salad called tororo served over sushi or to accompany rice. It is also sometimes used as the starch in certain types of Japanese soba noodles.

Where can I buy it?

Asian markets - particularly Super H Mart, where I photographed these recently.

Recipe: Nagaimo Pancakes: Courtesy of CloveGarden.com

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• The Basics