They are about 18 inches in length, so it is not without reason that they are called long beans when sold by the bunch at Chinese and Southeast Asian produce stands. Varieties with names like Fowl's Gut Bean and Yak's Tail can grow to a yard in length.
However, these ancient vegetables, which still grow wild in tropical Africa, are actually legumes. While they probably originated in Africa, some scholars feel they were taken there from Southeast Asia.
Since cookbooks often instruct to treat these as you would regular green beans it's a common misconception that they're related. Long beans, however, are close kin to the blackeyed pea -- some argue, simply a variety. In fact, blackeyed peas, much to the wonderment of non-Asians perusing Asian food stores, are a fixture of markets that stock Southeast Asian goods. Blackeyed peas and rice have been enjoyed for far longer in Malaysia than in Alabama.
Two varieties of long bean are available at Asian produce stands -- a light green type that is at its best from mid-May to mid-June, and a darker green one that peaks between mid-June and mid-August. Those expecting the sweet crispness of green beans will be disappointed. When briefly steamed or stir-fried, unless the flavors around them are assertive, long beans don't offer a lot of flavor.
They do, however, hold up well when added to a stew. Or in dishes such as the popular Szechuan "dry fried beans," they may be deep fried in very hot fat then cooked with chopped meat and other seasonings. True dry-frying, however, originally meant baking them in the sun under glass until they wrinkle, rather than immersing them in oil.
Even when hanging on the vine, long beans are never stiff and crisp like green beans. However, they shouldn't be terribly limp when you buy them. They'll keep for a week in the vegetable crisper.
SZECHUAN DRY-FRIED LONG BEANS
(4 to 6 servings with rice and another dish or two)
1 1/2 pounds long beans (about bunch)
2 cups plus 2 tablespoons peanut oil
1/2 pound ground pork
2 tablespoons chopped red chili peppers, seeds and all
1 tablespoon chopped ginger
1 tablespoon dark soy sauce
1 teaspoon sugar
1 teaspoon salt
1 tablespoon dry sherry or Shaoxing wine
Rinse and cut the long beans into 3-inch lengths. Heat 2 cups of oil in a wok or heavy skillet to nearly smoking. While it's heating, chop the ground pork briefly to a finer consistency, and put the chilies and ginger together, and set aside.
When the oil is hot, add the beans (make sure they are thoroughly dry), and cook 5 minutes or longer, or until they wrinkle. Then remove and drain.
Drain off the oil -- it may be strained and used again -- and re-heat the pan. Add 2 tablespoons of oil and the pork. Cook, stirring over high heat just until the granules are broken up and the meat changes colors. Add the soy sauce and stir for about 30 seconds, then add the chilies and ginger, and cook for another 30 seconds. Add the beans, sugar, salt and wine, and cook stirring until piping hot. Serve.