Neither from Jerusalem or an actual artichoke, this strange, knobbly vegetable is in fact the tuber of the sunflower Helianthus tuberosus. Originating from America, Jerusalem artichokes were cultivated in Europe in the early 1600s. High in iron and potassium, they’re a very healthy vegetable and good for diabetics due to their low glycemic index and low starch levels, making them a lower calorie alternative to potato. The only downside is the high levels of inulin Jerusalem artichokes contain, which the body's digestive enzymes cannot break down. This job gets left to bacteria in the gut, turning it into CO2. This can result in excess gas in some people; a little embarrassing at a dinner party!
Jerusalem artichokes are in season throughout the winter months in the UK, and can be found either as topinambour, which have a reddish purple skin with lots of knobbly bits, or as helianthus, which are a pale beige and normally straighter and therefore easier to peel. When peeling prior to cooking it is advisable to keep the Jerusalem artichokes in acidulated water to prevent them from discolouring. It is not, however, mandatory to peel them; just make sure you give them a good scrub first.