Cook noodles according to package directions until al dente. Drain and rinse under cold water. Toss with 1 teaspoon sesame oil to prevent sticking.
Heat wok or large skillet over high heat until smoking. Add 1 tablespoon vegetable oil and swirl to coat.
Add chicken in single layer. Let sear undisturbed for 1 minute, then stir-fry until nearly cooked through, about 3-4 minutes total.
Push chicken to side. Add remaining oil, garlic, and ginger. Stir constantly for 15 seconds until fragrant.
Add cabbage, carrot, and bell pepper. Stir-fry for 2-3 minutes until crisp-tender.
Mix soy sauce, oyster sauce, remaining sesame oil, sugar, and white pepper in small bowl.
Add cooked noodles and sauce to wok. Toss everything together for 1-2 minutes until well coated and heated through.
Stir in bean sprouts and green onions. Cook for 30 seconds more. Garnish with sesame seeds and serve immediately.