Growing and eating ocas (Oxalis Tuberosa)

What are ocas?

Ocas (Oxalis tuberosa) is extensively cultivated in Peru and Bolivia. It is also grown commercially in New Zealand where it is known as yam, and grows very well in the UK and Ireland. It has small edible tubers which are washed, and can then be boiled, roasted, stir fried, or even eaten raw in salads. The tubers have a pleasant sweet/ tangy flavour, Leaves are also edible, with a tangy flavour similar to that of sorrel. Indeed, ocas belong to the Wood sorrel family.

Why grow ocas?

They are very easy to grow. They give good yields, and are delicious to eat. And they even make a nice decorative border, with lots of flowers in early autumn!
They are still relatively unknown in Europe and are not grown commercially outside their native Andes, except in New Zealand, but this is starting to change. Dennis Cotter, of Cafe Paradisio fame, gives a few recipes for them in his last book "Wild garlic, gooseberies... and me", so they are a good crop to start growing now.
They store very well throughout the winter. Tubers left on a shelf in a shed were still perfectly edible in April, and grew when planted.
They are disease free, and you can save your own tuber seeds from year to year.

How to grow ocas?

Ocas are very easy to grow. They don't suffer from blight and seem to be very disease and pest resistant (although slugs will eat the tubers in the winter, so timing or harvest is important). The only thing required to grow oca is patience: they need a long growing season as the tubers don't start growing before the Autumn equinox. For that reason, they may not be suitable in areas where there's early frost, as this will kill them before the tubers have properly developed.
Ocas are basically grown like potatoes, although they are more shade tolerant, and in fact, will do better in partial shade. Plant them out after the last frost, at 30 - 40 cm spacing and at a depth of 5cm, and wait. After a few weeks, small stalks with clover like leaves will appear. Give them a weeding once they are big enough, and after about two months, earth up the stalks (this is optional, but recommended as it increases yields). That's all there is to do until the first frost kills the plants in November or December. It is time then to dig the tubers up. If you don't have early frost, let them in the ground till early December for the biggest yield. You can pluck a few leaves throughout the summer to add to your green salads.
Yields are on a par with that of potatoes.
If growing them at home, leave them in the sun for a few days once dug, as this sweetens the flavour.

How do I get started growing ocas?

You need to get tubers for planting!
Tubers are usually available in December and January from Macalla farm in Ireland. The The Real Seed catalogue also has some in the UK.

How to eat ocas?

Ocas are very versatile vegetables.
They have a slightly tangy taste and a delicious crunchy texture when raw. It is a good idea to leave them in the sun for a few days once dug, as this sweetens the flavour. The texture gets more floury, and the flavour sweeter, once they are cooked. They can be used raw in salads, boiled (the traditional way to cook them in their native Andes), stir fried, cooked in curries, stews or soups, steamed (and served with butter or honey) or brushed up with olive oil and roasted (the best way if you ask me). Oca cook more quickly than potatoes or even sweet potatoes, so check early on if they are done.
There's no need to peel them, just wash them (which is easy thanks to their slightly waxy skins).
The leaves can also be eaten and make an interesting addition to a green salad (although you shouldn't eat too much of them as they contain oxalic acid).

Oca links

Macalla farm, organic farm in Ireland (usually have ocas for sale)
Plant for a future oca page
The Real Seed catalogue (sells oca tuber seeds)
Information on growing ocas down under :)