Being exploited only by adventurous gardeners or by a few producers passionate about rare or forgotten vegetables, it is interesting to cultivate it, even when space is lacking because it adapts well to growing in pots.
The oca – Oxalis tuberosa or Oxalis crenata – has succulent stems, creeping then straightening which are easily layered by repeated hilling. The leaves are fleshy, trifoliate, bright green. The small, round, yellow flowers bloom sporadically from summer to fall. Sterile, they do not produce seeds. The exquisite tubers, the size of a pigeon’s egg – 3 to 6 cm – nippled, irregular, vary from yellow to red, passing through lovely pink tones, depending on the variety.
In practice, in the garden
Choose a sunny location or soft shade, fresh, light, loose soil rich in humus. In April May, in a row, plant a tuber every 50 cm. Hill up as it grows, keeping only 30 cm of stem clear. After a few weeks, leafy stems emerge from the ground. During the summer, the oca takes a bushy shape. When the days get shorter, the stems wither and lie down: cover them with earth. It is in contact with the earth that the tubers form, at the level of the stem nodes. The harvest begins in mid-November. Until then, if severe cold weather is forecast, protect this frost-prone plant with a forcing veil or otherwise risk losing the entire harvest. Once pulled out, the tubers are stored cool and in the shade like potatoes.
Although the varieties are numerous – there are more than 500 – they are not always easy to find at seed companies. Here are some of the most common, accompanied by their local names, for more of a change of scenery, oca being native to Peru and Bolivia, and cultivated on the high plateaus of the Andes. The type species, white oca (Uiakou’n) veined with pink, pink oca (K’hriy asunte) with white tip, yellow oca (Ayka kuru) with red reflections, carmine red oca (Ekmakou) streaked with white, purple oca (Oka negra) veiny red to purple in color; red oca…
In practice, in the kitchen
The flavor of the tubers is a hodgepodge of potato, sweet potato and sorrel. These small root vegetables can be cooked in many ways, always cooked, like potatoes. No need to peel them to put them in water, make puree, braise them, fry them or sauté them. Their slightly tangy side is well suited to preparations based on fish and white meats. If you don’t like too much acidity, leave them in the open air, in the sun, for two days, then boil them, rinse them before cooking them
A hint of history
It was at the beginning of the 19th century that oca arrived in Great Britain, where it almost replaced potatoes when the great famine raged in Ireland, late blight having destroyed them excessively. The cultivation of ocas was then considered and then abandoned, because it was too long and not very productive. Fortunately, the use of copper as a treatment solved the problem, and potato growing resumed.
OCA, since this episode, had almost been forgotten in Europe. But with the craze for forgotten vegetables, it is popular with curious vegetable growers and great chefs, while in Peru or Bolivia, its culture is in decline. Observed as a food for peasants, it loses a little more ground every day in the face of the “more refined” demands of the population.
Attention
Among perennial vegetables, some should be consumed in moderation, because they contain oxalic acids: oca is one of them, like sorrel and rhubarb. Oxalate crystals are not recommended for people suffering from rheumatism, gout or kidney problems. If this is the case, obviously avoid eating it every day, but don’t let that stop you from enjoying it with gusto as soon as you have the opportunity.
