Wednesday, 28 October 2009
Not from Jerusalem, nor are they artichokes. These are in fact the roots of helianthus tuberosus, which translates as the tuber-rooted sunflower. It is believed that the "Jerusalem" part of the name derives from "girasol", meaning to turn with the sun; as many flowers do. The artichoke part comes from a perceived similarity of flavour.
These are a very interesting vegetable, although not widely known. They are one of only two garden vegetables known to have originated in the Great Lakes region (the other is acorn squash) , so they are truly local in a way nothing else is. Also, because they store carbohydrates as inulin, they have a very unusual nutritional profile, and are often considered very appropriate for people with diabetes. However, the same inulin content makes them very prone to cause flatulence; they should be introduced to the diet fairly slowly if you are not accustomed to them.
If you look closely at the picture, you can see that there are two different colours of Jerusalem artichokes on the plate. Jerusalem artichokes, like potatoes, are grown from tubers which are clones, although in the Jerusalem artichokes the differences are very subtle and more of interest to the gardener than the chef. Once they are peeled, the remaining pale, creamy flesh is pretty much indistinguishable between varieties. Some varieties may be a bit rounder and smoother than others, making them easier to peel. I had a choice of two colours and I noticed that the darker red ones seemed more popular than the gold ones; there weren't many left for me to choose from when I bought them.
Unlike potatoes, they can be eaten raw, although I find them a tad starchy. They are crisp and juicy though, and would be a good source of crunch in salads or crudité plates. Quickly stir-fried, they make a good substitute for water chestnuts. In Victorian England, they became the basis of a popular soup called, inevitably, Palestine soup. They can be be steamed, boiled, fried or baked. Their flavour is subtle, but appealing. My mom says they remind her of jicama, and I can see the resemblance although they are not as delicately scented, I don't believe (it's been a good while since I've had a jicama!) Most people do peel them, but it isn't necessary; a good scrub will do.
I have not tried growing them, but I gather that they are both easy and difficult to grow, or rather, the difficulty lies in getting them to stop growing. They benefit from being dug and moved to new, enriched ground each year - they will produce larger, less knobby tubers this way - but if any bit of root is left behind in the old bed it will sprout and soon replace itself, so care must be taken when harvesting them. Even with care, you are likely to end up with permanent Jerusalem artichoke beds, so while I am interested in growing them I am going to think twice about where to put them. People describe them using words like "thug" and "bully", so be warned.
They should be planted in the spring, according to William Woys Weaver, and in mid-summer pruned to 18" in height then earthed up with rotted manure and mulch. I imagine this must delay the lovely golden blooms, but it should ensure good, big tubers. (Relatively speaking. Jerusalem artichokes are not so large as your average potato; golf ball size is typical, I would say.) Once the plant has been nipped by frost, the tubers can be dug up and enjoyed, or stored for later use.