Yautia (Xanthosoma) is a tropical plant and a member of the Araceae family along with taro and dasheen. All of these plants produce roots that are rich in starch and serve as a staple food for many people. The yam-like edible part of yautia is not really the root, but actually the major underground stem of the plant. There are more than forty species of yautia and the plant is also known as malanga, tannia or new cocoyam. It is native to wet regions in Central and South America. Yautia was shipped to Africa in the mid-1800s where it quickly became a staple food and remains so today. The plant is also especially popular in Cuba and Puerto Rico.
Yautia can be distinguished from other tropical roots by its pleasant strong and earthy flavor that is similar to nuts. The stems look like yams with their irregular, bulky shape and have a thin light brown skin. The inside firm flesh ranges in color from white to yellow and occasionally has pink streaks. If you can find some yautia, select those that are firm and unblemished. The stems do not keep especially well and can be stored at room temperature for only a couple of days. When you are ready to eat them, peel the skin and cut the flesh into pieces. Then rinse the pieces to remove excess starch and store them in cold water. Yautia can be baked, boiled, and steamed. The stems often disintegrate into mush when overcooked, so be sure to keep an eye on them toward the end of their cooking time. The stems can be mashed like potatoes, made into fritters, or sliced thin and deep-fried to make chips. You can use yautia in most recipes that call for potatoes, yams, and other root vegetables.
Raw yautia contains calcium oxalate crystals and saponins, which are acrid and can be highly irritating. These compounds are most prevalent in the skin of the stem. Heat will destroy these irritants, so yautia should always be cooked before eating it.
http://www.innvista.com/health/foods/vegetables/malanga.htm
http://www.fao.org/docrep/T0646E/T0646E0o.htm
http://www.botgard.ucla.edu/html/botanytextbooks/economicbotany/Colocasia/