In a medium bowl, soak the mushrooms in 1/2 cup cold water for 30 minutes or until softened. Drain and squeeze dry (reserve the soaking liquid for use in soups). Cut off and discard the stems and mince the caps. Wash the long beans in several changes of cold water and drain thoroughly in a colander until dry to the touch. Cut into 1/4-inch-long pieces to make about 3 cups. Rinse the preserved vegetable in cold water until the red chili-paste coating is removed and pat dry. Finely chop to make about 1/3 cup. Chop the Chinese sausage into 1/4-inch pieces. Dice the pork into 1/4-inch-pieces and sprinkle with 1/4 teaspoon salt. Stir to combine and set aside.
In a small bowl, combine the soy sauce, rice wine, sesame oil, pepper, 1/2 teaspoon sugar and 1/8 teaspoon salt; set aside. Heat a 14-inch flat-bottomed wok or skillet over high heat until hot but not smoking. Add 1 tablespoon vegetable oil, sausage and pork and stir-fry 1 minute. Transfer to a plate. Add the 1 tablespoon oil and mushrooms to the wok and stir-fry 1 minute. Add the remaining 1/8 teaspoon salt and remaining 1/4 teaspoon sugar and stir-fry another minute. Remove the mushrooms from the wok and add to the sausage mixture. Add the remaining 2 tablespoons vegetable oil and the green beans to the wok and stir-fry 1 minute. Cover for 20 seconds. Uncover, add 2 tablespoons water and stir-fry 10 seconds. Cover and cook 30 seconds. Return the sausage mixture and the preserved vegetable to the wok along with the scallions, cilantro sprigs and soy sauce mixture. Stir-fry 1 to 2 minutes or until the vegetables are just tender. Serve immediately.