One can surmise that the Chinese grew sprouts ages ago as a sort of instant vegetable that doesn't require a patch of land and proper weather. Few vegetables can be harvested in the dead of a bitter winter, as sprouts can, and they are a fine source of vitamin C.
But sprouts aren't quite the miracle food they were touted to be a decade or so ago.
According to Harold McGee in his "On Food and Cooking: The Science and Lore of The Kitchen" (Scribners, 1984, $29.95), their nutritional value lies between the raw bean (or seed) they started as and the mature green vegetable they would have become.
Two varieties of bean sprouts commonly are available at Chinese markets. Most common is the sprout of the green mung bean; also available is the larger, woodsy-flavored soy bean sprout. The Chinese also sprout and eat the broad (fava) bean, but it's rarely available commercially.
Mung bean sprouts should be purchased crisp and bright white without a trace of the brown that begins to color the root and "neck" of the sprout as it ages. In other than the homiest of home dishes -- before serving to guests for example -- the Chinese pluck off the head (bean) and tail (root) of the bean sprout. The task takes time, but makes a big difference in texture and appearance. In Hong Kong, fresh plucked bean sprouts in pearly white mounds are for sale daily. Blanching bean sprouts is sometimes recommended before using them, but isn't necessary. They should however be thoroughly rinsed.
If it's impossible to buy them the day you use them, store sprouts in a plastic bag in the vegetable crisper where they'll keep for a couple of days.
Soy bean sprouts, a tradition at Chinese New Year's, are longer and thicker than mung bean sprouts and they're topped with a full-sized yellow bean. They're often blanched and served tossed with a sesame oil dressing or stir-fried in simple combinations such as with mushrooms and bamboo shoots.
For anyone who wonders why home-grown bean sprouts are never as long and straight as those in Chinese markets, the secret is that commercial growers put a light weight over the beans for the sprouts to push up against. PORK WITH RED CHILES AND BEAN SPROUTS (4 to 6 servings)
Closer to a banquet dish than a simple stir-fry, this is attractive and delicious either wrapped in the tortilla-like pancakes traditionally served with Peking duck and mu shu pork, or served with rice.
5 to 6 ounces pork loin, carefully trimmed
1/2 tablespoon dark soy sauce
4 cups fresh (mung) bean sprouts
1 teaspoon salt
1 teaspoon sugar
1 tablespoon dry sherry or shaohsing rice wine
9 tablespoons peanut oil
1 cup fine matchstick shreds of hot red chile peppers
1 teaspoon sesame oil
Cut the pork into fine matchstick shreds, toss with the soy sauce and set aside. Pluck the heads and tails from the bean sprouts; rinse and dry them, and set aside. Mix the salt, sugar and wine, and set aside.
Heat 5 tablespoons oil in a wok or skillet. When hot, add the pork and stir rapidly just to separate the shreds, no more than 15 seconds.
Remove to a collander and drain. Discard the oil and wipe out the pan. Re-heat the pan, add the remaining 1/4 cup oil. When hot, add the bean sprouts and peppers and cook, stirring for about 30 seconds. Add the seasoned wine and toss briefly to coat; then re-add the pork and cook, stirring just until the mixture is heated through. Turn off the heat, dribble over the sesame oil and serve.