Slice the beef sirloin into thin strips and marinate with soy sauce, oyster sauce, rice wine, cornstarch, sesame oil, and white pepper for at least 30 minutes.

Cook the egg noodles in boiling water according to package instructions until al dente (4-6 minutes). Drain and toss with sesame oil.

Whisk together hoisin sauce, dark soy sauce, brown sugar, rice vinegar, ginger, and garlic in a bowl to prepare the sauce.

Heat oil in a wok and stir-fry the marinated beef for about 3-4 minutes until browned and cooked through. Set aside.

In the same wok, sauté minced garlic and ginger for about 30 seconds until fragrant.

Add sliced bell peppers and onions, and stir-fry for 2-3 minutes. Then add broccoli florets and stir until bright green and tender.

Pour the prepared sauce over the vegetables and simmer for 1-2 minutes. Optional: thicken with a cornstarch slurry.

Return the beef to the wok, add the cooked noodles, and toss everything together until evenly coated and heated through.

Garnish with scallions and sesame seeds if desired. Serve hot and enjoy!