Bring a pot of water to boil for the ramen noodles.
While water is heating, prepare the sauce by mixing soy sauce, oyster sauce, sesame oil, sugar, and white pepper in a small bowl. Set aside.
Heat 1 tablespoon of vegetable oil in a large wok or skillet over high heat. Add chicken pieces and stir-fry until golden brown and cooked through, about 5-6 minutes. Remove chicken from the pan and set aside.
In the same pan, add remaining oil. Stir-fry bell pepper, snap peas, and carrot for 2-3 minutes until crisp-tender.
Add minced garlic, ginger, and white parts of green onions. Stir-fry for another 30 seconds until fragrant.
Meanwhile, cook ramen noodles in the boiling water for 2 minutes (slightly undercooked). Drain well.
Add the cooked chicken back to the pan with the vegetables. Toss in the cooked ramen noodles and sauce. Stir-fry everything together for 2-3 minutes until well combined and heated through.
Garnish with the green parts of the sliced green onions and serve hot.