No, they aren't from the Holy Land and they aren't an artichoke. In fact, they are part of the sunflower family, which isn't surprising when you see their tall stems and small but bright yellow flowers. However, nutty-flavored Jerusalem artichokes (sometimes called sunchokes or sunflower chokes) are easy to grow, harvestable most of year (including winter), and healthy.
Perhaps the Jerusalem artichokes most noted characteristic is that their edible tuber contains inulin (not insulin), which makes it's suitable for those not wanting to spike their blood sugar, including diabetics. The tubers are also high in potassium, iron, and thiamene and help maintain good bacteria in the digestive tract (because they contain a natural pro-biotic).
During the summer, Jerusalem artichokes produce abundant cheery yellow flowers. When the flowers die down after the first frost, the roots are perfect for harvesting. The plant's one fault may be that it grows too easily. One friend told me a piece of the tuber tossed in her compost pile quickly developed into a plant. And others remind me the plant is invasive. My solution to the latter is to grow Jerusalem artichokes in a container or grow bag. Another solution is to cut back the flowers, which in turn results in bigger edible tubers.
It can be a challenge to find Jerusalem artichokes in nurseries. However, they can usually be found in grocery stores; if you have trouble finding them there, call around to local health food style grocery stores.
Plant the tubers as early as January and as late as May, about 5 inches deep, in full sun. Place tubers 18 inches apart. The plants will grow tall, so bear this in mind or you may inadvertently shade other edibles.
Although you can harvest them anytime, it's best not to harvest before October or so; you'll get bigger tubers to eat. In addition, cold temperatures improve the flavor of the tubers. The crop can be left in the soil and dug up throughout winter. While harvesting, if you find any small tubers, let them remain in the soil to create the next year's crop.
To eat Jerusalem artichokes, scrub them clean. There's no need to peel them. One easy way to eat them is to slice them like French fries, toss with olive oil and seasonings, and bake until golden. You can also slice them into rounds and fry them like potato slices. For more cooking ideas, check out the Jerusalem artichoke recipes at Epicurious.com.