Jerusalem artichokes are neither artichokes, nor related to Jerusalem in any way. The plant is actually a variety of sunflower (you eat the tuber of the plant) so the name was derived from the Italian word for sunflower, girasole which, well, kind of sounds like Jerusalem. To avoid confusion, many growers and markets often refer to it as a sunchoke.
Sunchokes are in season from October through March, so if you've never tried them, now is the time. They're also native to the east coast of the United States, so for those of you east-coasters looking for a guilt-free crop, this one's for you. You can probably find some at your local farmers' market.
Suncokes are lumpy and brown tubers that look a lot like ginger root. They have a nutty, crunchy, sweet flesh so they are great raw, shaved thinly over salads. Roasting them nestled in a thick bed of salt is another common preparation. Jerusalem artichokes are lovely cooked and puréed into a silky winter soup. They are an excellent source of iron.
Some Jerusalem artichoke/sunchoke recipes:
• Sunchoke Soup with Pumpkin Seeds from this month's Bon Appétit (November 2008)
• Smoked Brook Trout with Sunchoke Purée and Cippolini Onion from Chocolate & Zucchini
• Shaved Sunchoke Salad with Parmesan and Arugula from Food & Wine (May 2006)
• Jerusalem Artichoke Pickles from Gourmet (June 2008)