Rinse and drain the mung bean sprouts. Peel and chop the onion. Peel the carrots and cut on the diagonal into 1/4-inch pieces. Shred the cabbage. Cut the chili peppers in half lengthwise, remove the seeds and finely chop. Peel and finely chop the garlic.
Cut the barbequed pork (if using) into thin pieces. Cut the sausages (again, if using) on the diagonal into 1/2-inch pieces. Steam the sausages for about 10 minutes. Soak the shrimp in lightly salted warm water for 5 minutes.
In a small bowl, mix the oyster sauce, light and dark soy sauce and brown sugar. Set aside.
Heat 1 tablespoon oil in a wok over medium heat. Add eggs and scramble. Remove. Heat 2 tablespoons oil in a wok over medium-high heat. Add onions and carrots and stir-fry until the onion is softened. Add the chiles and garlic and stir-fry until fragrant. Add the shrimp and stir-fry unti they turn pink. Add the sausages and the barbequed pork. Stir in the cabbage. Remove and clean out the wok.
Heat 1 tablespoon oil in a wok over medium heat. Add the eggs and lightly scramble. Clean out the wok.
Heat 2 tablespoons oil. Add the rice noodles and cook for 2 minutes, stirring continuously. Push up to the sides and add the sauce in the middle. Heat to boiling, then mix in with the noodles. Add the other ingredients back in the pan. Stir in the mung bean sprouts. Cook for 30 seconds then stir in the egg. Continue cooking, adding a bit of water or chicken broth if the mixture gets too dry. Season with the salt and pepper. Serve hot, garnished with the cilantro.