Jerusalem artichokes can be found in most good quality greengrocers. Avoid those that have a greenish tinge. Make sure they are not sprouting, or are shrivelled or mouldy.
Keep the tubers wrapped in plastic and refrigerate. They will keep up to two weeks, but it's always best eat them as fresh as possible for the best flavour and nutrition.
Tips & Tricks:
Scrub the artichokes clean with a vegetable brush. Since much of their nutrients are stored just under the skin, it's best not to peel them. Once cut, they discolour quickly, so it's best to cut them close to serving time, or cut and immerse them in water with lemon or vinegar to prevent oxidation. Cooking them with the skins on may cause a darkening of the skins because of their high iron content.
Roast them whole or sliced. Toss them in a bowl with a little extra virgin olive oil and place on a baking sheet. Set the oven temperature at 180 and bake for 30 to 45 minutes for whole, and 20 to 25 minutes for sliced, turning them half way through. Season with salt and pepper to taste.