Mix the oyster sauce, soy sauce, sesame oil, and corn starch in a bowl. Mix in the minced ginger, garlic, and chiles. Slice the scallions and add them to the bowl (discarding most of the green). Add the meat, mix thoroughly, and marinate for thirty minutes.

Trim the ends of the long beans and cut them into pieces of a manageable length. (Four to five inches is about right.) Heat the peanut oil in a large wok over high heat. Add the beans and cook for eight to ten minutes, stirring occasionally, until done but still crisp.

Remove the beans from the wok, set aside, and discard all but two tablespoons of the oil. Reheat the remaining oil, add the beef and marinade, and cook until barely done. Return the beans to the wok and stir until they are heated through.