Prep the chicken: Slice the chicken thinly across the grain. In a bowl, mix 1 tablespoon soy sauce, 1 teaspoon cornstarch, and half the black pepper. Toss in the chicken and let it sit 10–15 minutes while you prep the vegetables.

Make the sauce: In a small bowl, combine remaining soy sauce, dark soy (if using), oyster sauce, Shaoxing wine, rice vinegar, brown sugar, remaining black pepper, and chicken stock. In another small cup, stir 1 teaspoon cornstarch with 1 tablespoon water to make a slurry.

Heat the pan: Set a large skillet or wok over medium-high heat. Add 1–2 tablespoons oil and swirl to coat.

Sear the chicken: Add the chicken in a single layer. Cook 3–4 minutes, stirring once or twice, until just cooked through and lightly browned. Transfer to a plate.

Stir-fry aromatics: Add another tablespoon of oil if needed. Toss in the onion, bell peppers, garlic, and ginger. Stir-fry 2–3 minutes until crisp-tender and fragrant.

Combine: Return the chicken to the pan with the vegetables. Pour in the sauce and bring to a simmer. Stir the cornstarch slurry, then add it to the pan. Cook 1–2 minutes until the sauce thickens and coats everything.

Finish: Stir in green onions and sesame oil. Taste and adjust with more pepper or a pinch of salt if needed.

Serve: Spoon over hot rice or toss with noodles. Add extra cracked pepper on top for a bolder kick.