Oca Tubers

Oca (pronounced oh-kah) is an interesting heirloom from the Andes region in South America. As is the case with other crops from this area, it was a staple food in the Inca empire. (see p 83-91 in The Lost Inca Crops)

It is a perennial bushy plant in the wood sorrel family (Oxalidaceae) that has striking leaves shaped similar to shamrocks. The leaves are edible and have a lemony flavour that can, for example, work well in salads. Tubers are the main crop and they look a bit like a chunky fingerling potatoes or small carrots.

It is very easy to grow Oca in Ireland and since the trifoliate leaves look a bit like Irish shamrocks it is also a nice ornamental plant.

The flavour is one of oca’s most distinctive traits. Raw, it is quite sharp due to oxalic acid content — similar to sorrel. Andean cooks traditionally sun-dry fresh tubers for several days before cooking, which converts some starches to sugars and mellows the acidity considerably, leaving a sweeter, slightly nutty flavour.

Culinary ideas:

Fried or roasted — The texture becomes soft, somewhere between a roasted potato and a carrot with a nice mild tang to it
Boiled / Stews / soups — Slightly softer than roasted, but similar flavour
Raw in salads — Kind of like a crunchy radish with a tang rather than mustard heat.
Pickled — We have not tried this but the crunchiness when raw should lend itself to this
Candied — We have not tried this but the tanginess should make it an interesting sweet-sour contrast

Plant out in late March to late April, once the worst frost risk has passed.
Harvest in late October through November, ideally after the first light frost which sweetens the tubers slightly by converting starch to sugar, but before a hard killing frost.

Additional information
Oca is native to the Andean highlands of South America where it has been cultivated for at least 8,000–10,000 years, making it one of the oldest domesticated crops in the Americas. It was a staple food of  Andean civilisations like the Inca alongside potato, ulluco, and mashua — the four principal Andean tuber crops. The Inca relied on it heavily as a high-altitude food source, as it thrives at elevations of 3,000–4,000 metres where many other crops struggle.