If you have a decent fruit-and-veg stall near you, or an adventurous supermarket, you might have noticed some mysterious knobbly things knocking around at the moment, probably lurking vaguely sinister and mostly ignored, somewhere near the parsnips. They're about the size of a small potato, with odd, pink-tinged, scaly skin, and as I said, they're knobbly. Some of them might be cracked. In fact, they look like this:



And they're jerusalem artichokes. And if you haven't eaten them, which is quite likely, you probably give them a nervous glance and walk on by.

But don't! Because, dear reader, they are delicious, low in starch, and make one of the best and easiest soups in the world ever, if you have a blender.

If you look up jerusalem artichoke, the first thing you'll see is that they aren't artichokes. They're a kind of sunflower, and if you try to grow them, apparently you end up with a spiky-leaved triffid about 8ft tall that can withstand a gale-force wind on a cliff edge. But the tubers, weird-looking as they are, taste slightly musky and slightly nutty and fantastic.

There's all sorts of stuff you can do with them. Always peel them first; you can roast them like potatoes, and they go soft and fudgy on the inside and slightly crisp on the outside; you can eat little ones sliced and raw in a salad, where they'll crunch like water chestnuts. Or, as I said, you can make soup.

Here's what you do. For two people, you'll need three or four large-sized lumps of jerusalem artichoke. Try to find the less knobbly ones, as they're easier to peel.

Chop a medium-to-large onion, and chuck it into a large saucepan where you've been heating about a tablespoon of olive oil and a walnut-sized knob of butter. Let the onion cook gently, barely sizzling, and add salt and black pepper and a bayleaf and/or a teaspoon or so of thyme leaves if you have them. While that's going on, peel the artichokes, slice them into evenly-sized chunks, and add them to the pan with about half a litre of chicken or vegetable stock — enough to cover them. Put the lid on the pan and simmer for 20 minutes, then remove the bayleaf and liquidise. The resulting soup will be extraordinarily velvety and aromatic. You can add some cream if you like but you don't need to. If you have some, you can even drizzle in a few drops of truffle oil. But you don't need to.

If it's cold outside, this is one of the best things you can have around. Warm up some crusty bread and dig in.

One warning, though: they make you fart.