Originally from the Andes, oca was introduced to Europe and the South Pacific in the late 1800's as a potato competitior. It's become so prolific in New Zealand that some people call it "New Zealand Yam." It's available in the fall, and all parts of the plant are edible; the shoots, the leaves, and the tubers. The tubers are usually cooked before eaten, but unlike potatoes and yams, they can be eaten raw.
It has a slightly tangy flavor and a crunchy texture when raw. When cooked, it is starchy like a potato. The Incan varieties were purple and yellow in color, and the New Zealand ocas tend to be bright pink. It is a versatile vegetable and can be baked, boiled, fried, cooked in soups, stewed, and braised.
Strange New Vegetable: Yacon
(Image: Eric Hunt via Wikimedia Commons)