Slice the beef into strips and marinate with salt, white pepper, baking powder, vinegar, soy sauce, corn starch, and sesame oil for 20 minutes. In a bowl, mix together soy sauce, oyster sauce, sugar, white pepper, sesame oil, chicken broth, and corn starch to prepare the sauce. Mince the garlic and ginger, and cut the broccoli into small pieces. Cook the noodles in a large pot of boiling water, drain, and set aside. Blanch the broccoli in boiling water for 1 minute, drain thoroughly, and set aside. In a pan, heat 4 tablespoons of oil over high heat and stir-fry the beef for 2-3 minutes, then remove from the pan. In the same oil, stir-fry the garlic and ginger for 15 seconds, then add the broccoli and stir-fry for an additional 30 seconds over high heat. Add the beef and noodles, pour in the sauce, and stir