Taro roots are a type of corm that are high in carbohydrates and vitamins and often are compared to tubers such as potatoes. There are a large number of different types of taro roots, although the name is used generically to refer to all of them. The corms can range in size from fit-in-one's-palm to 1 foot (about 30 centimeters) or more in length. When harvested and trimmed for sale, taro roots have a thick, brown skin that can be covered in small hairs or needles, while the inside of the root is a very pale color sometimes tinged with purple. In cooking, the root is a common staple in many countries, including Indonesia, India, Japan and Africa, and can be cooked in much the same way as a potato, although it has a slightly sweeter, nuttier flavor and a unique undertone that some find unpleasant.
A substance known as calcium oxalate crystals can be found in taro roots. Different varieties, and even differently grown roots of the same variety, can contain much higher levels of the crystals than others. Not all roots contain harmful levels. When handling and eating taro roots, the crystals can cause irritation resulting from an allergic reaction to the substance and from physical contact with the crystals, which can create tiny abrasions that result in redness, irritation and potential problems such as kidney stones. For this reason, the roots should only be eaten once they are cooked and have been peeled, and they are safer to handle once boiled — after cooking reduces the amount of crystals in the corm.
Choosing taro roots from a market is similar to choosing potatoes. They should be firm and feel heavy when held. The roots and hairs on the surface should be pliable and not overly dry or brittle, which could indicate that the root is old. Roots that have small knobs on the surface are sprouting new growth, which some cooks find undesirable, although the knobs can be eaten. Taro that is mushy or has an off odor should be avoided.
One of the most well-known taro recipes is poi, and it is made in Hawaii and Indonesia as an inexpensive meal. It is prepared by boiling taro roots until soft and then mashing the roots with some water and sometimes sugar until it forms a paste. In soups and stews, taro root can be used as a starchy thickener similar to potatoes, as is the case in some Japanese stews that include fish and other meats. A very popular way to prepare taro roots, especially in areas of India, is to slice the roots into small discs; coat each one in cumin, turmeric and salt; and then fry the rounds in oil until crisp on the outside. They then can be eaten as a snack or side dish.