Prep the chicken: Thinly slice the chicken across the grain. Toss with 1 tablespoon soy sauce and 1 tablespoon cornstarch. Set aside for 10 minutes while you prep the sauce and vegetables.

Make the sauce: In a small bowl, combine remaining soy sauce, oyster sauce, dark soy (if using), sesame oil, brown sugar, rice vinegar, chicken stock, and white pepper. Stir until the sugar dissolves.

Prep aromatics and veggies: Mince garlic and grate ginger. Slice cabbage, carrots, and peppers. Separate green onion whites from greens.

Cook the noodles: Boil according to package directions until just shy of tender. Drain and rinse briefly under cool water to stop cooking. Toss with a drizzle of oil to prevent sticking.

Sear the chicken: Heat 1 tablespoon oil in a large skillet or wok over medium-high heat until shimmering. Add chicken in a single layer. Cook 2–3 minutes per side until just cooked through and lightly browned. Transfer to a plate.

Stir-fry vegetables: Add another tablespoon of oil if needed. Add green onion whites, garlic, and ginger. Stir 30 seconds until fragrant. Add cabbage, carrots, and peppers. Stir-fry 2–3 minutes until crisp-tender.

Combine: Return chicken and any juices to the pan. Add cooked noodles. Pour in the sauce and toss with tongs for 1–2 minutes until everything is coated and glossy. Add green onion tops and a splash of chili oil if you like heat.

Taste and adjust: If it needs more salt, add a splash of soy sauce. If you like more shine, add a teaspoon of oil. Serve hot.