In this month’s review of Le Grand Bistro, I praise many of John Broening’s dishes. Among them, the house-made mustard spaetzle. While tender pieces of the German dumpling, Riesling-braised pork shoulder, and spinach were all familiar enough flavors, the entrée arrived topped with something more obscure: the bright green shoots of an oca plant. Oca (oxalis tuberosa) was new to this one-time research editor, and so I did a little digging.
Broening used the plant’s young, clover-shape leaves, but the small tuber itself is a potato-like tuber indigenous to South America. Technically a cousin of wood sorrel, oca was historically used in the cookery of the Inca and Mayan civilizations of the Andes mountains, “where it is second only to the potato as a root crop,” Alan Davidson wrote in his Oxford Companion to Food. Also known as a “New Zealand yam” (where it is successfully grown), the vegetable is knotty—similar to a Jerusalem artichoke—and its waxy white, pink, or red flesh is entirely edible. Some eat the acidic tuber raw, others use it to add zing to soups, and many cook it as you would a potato. When sun-dried, the diverse crop even turns sweet. When I tasted the fresh oca shoot at Le Grand it added a pleasant bite of lemon to Broening’s spaetzle.
Plant It. According to Davidson, oca is “easy to propagate, and tolerates poor soil, high altitudes, and harsh climates.” Sounds like a pretty familiar list of growing conditions. Perhaps this Colorado vegetable gardener will give the perennial a try. Eric Skokan, the chef-owner of Black Cat and Bramble & Hare restaurants in Boulder and the most well-read area farmer I know, agrees that oca seems to be a good fit for Colorado. He does, however, warn "the virus and pests that follow the plant seem troublesome." Commercial farmers should be sure to find certified disease-free seeds.
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