I am forever on a quest for the ultimate rare and unusual plant and if it is edible, all the better. At the 2011 Heirloom Expo in Santa Rosa, I came upon a poster that described the oca (Oxalis tuberosa ‘Oca’) as a tuber native to the southern Andes. Also known as ocha, oka, quiba, apilla or New Zealand yam, it was introduced to Europeans in the early 19th century and to New Zealand in 1860 where it is now a common vegetable. Oca is now second only to the potato in agricultural importance in Bolivia and Peru. With lush clover-like foliage, attractive yellow trumpet-shaped flowers, easy-to-grow and delicious colorful tubers to harvest – what more could I ask from a plant? As Sherlock Holmes would say, “the game is afoot!” and I began my obsessive search for the oca, one of the so-called “lost crops” of the Incas.

My quest ended in success when I was able to locate oca at Annie’s Annuals in Richmond, CA and I discovered there are many varieties. These bear tubers ranging in colors from cherry-red, pink, purple, cream and yellow with a taste similar to potatoes (only smaller in size), but with an additional bonus of lemon, sour cream or sweet yam flavor. Belonging to a different family than the potato, it is resistant to blight and other pest and disease problems.

I planted the oca in full sun in a raised bed filled with well-draining, amended soil in the spring and watered and fertilized it sparingly (translation: whenever I remembered to water and feed it or whenever the foliage had collapsed). Tubers began to form in the late fall and when the top foliar growth died back in January (depending on where you live, this may occur as early as November or December), I spotted several colorful shoulders peeking out above the soil and harvested them, leaving a few “baby” tubers in the soil to develop new plants in the spring (below USDA zone 7, dig up the tubers in late-fall or early winter and re-plant in the spring). It is always a pleasure to harvest fresh vegetables in the winter, plus oca stores perfectly in a cool, dark, dry place.
Oca is an excellent source of carbohydrates, phosphorous, iron, essential amino acids that promote the health of muscles, organs and skin, but the raison d’être for growing it is the taste. You don’t need to peel the fat-fingered, waxy, tuber skins and they wash easily. They make a delicious, raw addition in salads and turn a pale yellow color when boiled, mashed, fried or roasted. With a splash of olive oil and a smidgeon of salt and pepper, mmmmmm!