What are ocas?
An Excerpt from Eco Farm:
Ocas (Oxalis tuberosa), grown commercially in New Zealand where it is known as Yam, is a tuber root crop from the Andes where it is a staple food, second only to potatoes.
Ocas belong to the Wood sorrel family.
Why grow ocas?
They are very easy to grow, give good yields, and are delicious to eat. And they even make a nice decorative border, with lots of flowers in late summer and 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 desease 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. 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 40 - 50 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. Wait for about a week after the plans have died, then 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.
I parboiled these ocas for 10 minutes then tossed with olive oil, S&P, placed on cookie sheet in broiler til cripy. The flavor is the most complete of any root vege i have tasted. No seasoning needed. This vege, native to S. America, i am sure will do will in Central Texas. I want to learn to cultivate this species.
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, 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 cooks more quickly than potatoes or even sweet potatoes, so checki 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
More info can be found at this link.