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Oca

Will the oca ever make it big in Europe? It ought to. It could…and I for one will be cheering when it does. This small tuber grows well enough here, but its real home is far, far away, up in the chilly heights of the Andes. And in Bolivia, Ecuador and Peru it is rated almost as highly as its compatriot, the potato. I first came across oca in a market north of Quito, the capital of Ecuador. It was the last stop of our holiday, so back came my haul of oca in the suitcase (smuggled in, if you must). We ate some, we grew some. We loved them. Almost end of story.

In fact that would have been the end, if I hadn’t spotted oca for sale here at home a couple of times in the past decade. If you are blessed enough to stumble across a rare basket of oca up for grabs, take them at once. The flavour of the fresh tuber lies somewhere between that of a new potato and a tart green apple, with a mealy, soft texture. Very good and just unusual enough to be interesting, without being weird.

The tart, appley tang comes courtesy of a splash of oxalic acid. If this sounds dismaying, reflect that this same acid gives rhubarb its distinctive sourness, far more astringent than the humble oca. Mind you, there are literally hundreds of varieties of oca grown down the backbone of the Andes and they vary from highly acidic to incredibly mild. The sharper varieties are not eaten fresh, but given a ‘soleado’, or a sunning. Left out in the sunshine for up to two weeks, the acidity dampens right down and starches turn to sugars. The result is an even smaller tuber, but with a startling sweetness closer to a sweet potato than any mouth-puckering stem of pink rhubarb. Dehydrated and frozen oca, known as ‘chaya’, are stashed away for leaner times.

The oca has travelled less than many vegetables, but it has at least dashed across the oceans to New Zealand where it is grown commercially in a small way. Here it is known simply as the New Zealand yam, despite not being a yam at all, or Maori potato, or more interestingly, as ‘uwhikaho’, or ‘uwhi’ for short.

Practicalities

BUYING

The commonest of oca, the ones that I’ve come across, are relatively small – say about 10cm (4in) long – have a waxy reddish skin and a crinkled form. In fact, they look a little like pink fir apple potatoes. Unlike most vegetables, freshness is not critical. Smooth skinned, plump oca will be gifted with a more distinct note of acidity than those that are beginning to shrivel a little having had time to develop more sweetness. In other words, this is a two-in-one vegetable, which is a rare and delightful gift from Mother Nature. So, as long as they have been stored well, wrinkles are not to be derided. Soft damp patches or worse still, a hint of mould, are not good things on the other hand. However, since you are not likely to come across oca frequently, you can’t really afford to be too choosy. Just throw out any that are beyond saving.

Oca, as you may well have inferred, keep well in the right conditions. The vegetable drawer in the fridge is just fine, but if the sun is shining, you might prefer to spread them out on trays outside (cover with muslin if you have some to hand, to protect from flies) to sweeten up a little. You can even freeze them – not a bad idea if you’ve found a rare clutch of oca for sale. As with any other vegetable, damp is destructive, so keep them dry.

COOKING

Oca can be eaten raw, especially the sweeter sunned ones, say in a salad, or cut into strips to dip into a chillied tomatoey dip perhaps. I prefer them cooked, exactly as you would a potato. In other words, rinse them, trim off ends, but don’t even attempt to peel. Then boil them in salted water until tender. They can also be roasted in the oven, coated in a little olive oil to prevent drying out, or steamed, or sautéed. They make heavenly crisps, but perhaps that is something to save for a time when oca have hit the big time and are as widely available here as they are in the highlands of Ecuador.