Taro is an important part of the nutritional, agricultural and even spiritual traditions of the Hawaiian people. There were reportedly 300 named varieties of taro under cultivation at one time in Hawai`i. The most traditional food made from taro in Hawai`i is poi -- cooked, pounded taro root, often slightly fermented. Visitors to the islands rarely find it to be a treat, rather more of an acquired taste.
Not all taro is edible and it should not be eaten raw! Ornamental varieties are usually NOT edible. Colocasia esculenta and Xanthosoma sagittifolium are edible (my only personal experience is with C. esculenta). A good-quality taro corm will be firm and dense.
Most edible taro has irritating, needle-like crystals (oxalic acid), and must be cooked to dissolve it. Undercooked taro root and taro leaves can cause extremely unpleasant itching in your mouth. Even handling the corms can cause itchy skin for some people (I'm very sensitive to it while my husband doesn't react at all). Wearing rubber gloves is a good idea. If you get unlucky:
In Hawai`i, Bun Long ("Chinese") taro is usually used for recipes that need less cooking time, such as taro chips, as it has the least amount of oxalic acid. This taro has a distinctive reddish dot on the leaf where it meets the stem and dark purple fibers in the corm.
Basic cooking method for taro corms:
Once cooked, it can be served just as you would potatoes -- chunked or mashed, put in soups. It is best served hot, as it can get rubbery when cold.
Leaves also need to be cooked thoroughly. Remove the stems and fibrous veins before cooking. Try seasoning some fish and wrapping it in taro leaves, then ti leaves (or corn husks or parchment paper if the others are not available), then foil, and baking for an hour or so - delicious!