Oxalis tuberosa
By Jeremy Trombley
Like the potato, oca is one of the most important root crops of the Andes. It produces small, rough tubers that can be used in a variety of ways and have a range of flavors. Unlike the potato, however, oca has been largely ignored outside of South America, but it is gaining some interest in recent years.
Oca tubers are much smaller than potatoes. They have a rough, waxy outer coating and come in a variety of colors. The plant requires a long growing season, and are best started well before the first frost and must be kept warm through the later months of the year until the tubers can be harvested in December. The oca plant is not related to either the potato or the sweet potato, but rather it is related to the European wood sorrel, which is commonly utilized as a leafy green.
The word oca is derived from the Quechua term used for the plant, oqa. The tubers are still common in the andean region, but largely failed to make it out of South America due to the long day length that it requires. However, it is grown commercially on a large scale in New Zealand where it is often referred to as the New Zealand yam. New Zealand farmers have developed many different varieties over the years, and some of these are suitable for planting in temperate regions of the northern hemisphere.
Oca can be used much like a potato and other root crops. It can be boiled, baked, or fried and it is often consumed in soups or stews. However, some oca is so sweet that it is often consumed on its own and is often regarded as a fruit for this reason. In some cases, the freshly dug tubers are too acidic, but this taste will disappear if they are left in the sun for a few days. In Mexico, oca is often eaten raw with a dash of salt, hot pepper and lemon.
Davidson, Alan. The Oxford Companion to Food 2nd Ed. 2nd ed. Oxford University Press, USA, 2006.
Weaver, William Woys. “You Can Grow Oca!.” Mother Earth News 2007. 6 Feb 2009 http://www.motherearthnews.com/Organic-Gardening/2007-08-01/Hot-to-Grow-Oca.aspx.