Prep everything first. Noodles go on to boil or soak according to package, chicken is sliced, garlic is minced. Mise en place saves you from the panic sweat mid-sizzle.
Heat a large skillet or wok over medium-high heat. Add 1 tablespoon oil, then sear the chicken until browned and cooked through. Remove and set aside.
In the same pan, add another teaspoon of oil if needed. Toss in garlic and vegetables. Stir-fry 2–4 minutes until crisp-tender and fragrant.
Return the chicken to the pan. Pour in soy sauce, oyster/hoisin (if using), rice vinegar, honey, and ketchup. Stir well to coat everything. Let it simmer 1–2 minutes to meld the flavors.
Add the cooked noodles. Toss vigorously so every strand gets a glossy, sticky glaze. If the pan looks dry, splash in a splash of water or stock to loosen just a touch.
Finish with chili flakes or sriracha if you like heat. Taste and adjust saltiness and sweetness. Remove from heat.