Soak the rice noodles in warm water for 20 minutes; drain.
Heat 3 tablespoons oil in a wok or large heavy skillet over medium high heat. Saute noodles for 1 minute. Transfer to serving dish, and keep warm. Add remaining 2 tablespoons oil to skillet, and saute onion, garlic, ginger, shrimp and pork for 1 minute. Stir in bok choy, oyster sauce and chicken broth. Season with pepper flakes. Cover, and cook for 1 minute, or until bok choy is wilted. Spoon over noodles, and garnish with minced green onion.