Heat vegetable oil in a large skillet or wok over medium-high heat.
Add sliced chicken and cook until browned and cooked through. Remove and set aside.
Add garlic and ginger to the skillet and sauté for 1 minute.
Add bell pepper, carrots, and snow peas. Cook for 3-4 minutes until tender-crisp.
Return chicken to the skillet along with cooked noodles.
Pour in soy sauce, oyster sauce, hoisin sauce, and sesame oil. Toss everything to combine.
Cook for another 2-3 minutes until heated through. Garnish with chopped green onions and serve.