Above ground, the plant (which is actually an herb) is a very small perennial, only growing about 8 to 12 inches high (20 to 30 cm.) Its stems can be yellow and green or purplish. It is propagated by replanting its tubers.
The edible tubers that grow underground look like long, miniature salad potatoes. The shiny skin can be red, purple, yellow or white. The flesh is firm and white. A few varieties taste a bit tart, but most don’t, and some are even quite sweet. Care has to be taken in digging them up, as they are a bit more fragile than potatoes. After harvesting, they are sometimes dried in the sun to make them even sweeter.
A few varieties can be eaten raw. Raw, they are tart and crunchy, and usually are sprinkled with salt, lemon and chopped chile, or served fresh in salads. Mostly, though, they are baked, boiled, fried or roasted. They can also be pickled.
New Zealanders have really taken to Oca since the 1980s, even serving them roasted with their roast lamb.
The leaves can also be eaten.
Oca is a distant relative of the Shamrock. Some say the leaves even taste like Shamrock, but if you’ve never been tempted to chomp into someone’s St Patrick’s Day centrepiece, you may never know.
Oca is grown throughout Latin America, where it is seen as a poor person’s food. In some places in Latin America, Oca rates close to potatoes in popularity amongst the poor.
Good source of iron and calcium. The leaves contain oxalic acid, as does spinach, which can hinder calcium absorption, but at levels far below those of spinach.
Oca is probably native to what is now Peru. It was first introduced into New Zealand in the 1860s.