1Bring a large pot of salted water to a boil. Cook noodles according to package directions until tender, then drain and set aside.
2In a small bowl, whisk together soy sauce, oyster sauce, sesame oil, rice vinegar, and water.
3Heat 1 tbsp vegetable oil in a wok or large skillet over medium-high heat. Add chicken and cook, stirring occasionally, until golden and cooked through, about 6–7 minutes. Transfer to a plate.
4Add remaining 1 tbsp oil to the wok. Stir in garlic and ginger, cooking until fragrant, about 30 seconds.
5Add bell pepper, snap peas, and carrot. Stir-fry for 3–4 minutes until vegetables are tender-crisp.
6Return chicken to the wok. Add cooked noodles and sauce, tossing everything together until coated and heated through, about 2 minutes.
7Divide among bowls and garnish with green onion. Serve immediately.