Marinate the Chicken: In a bowl, mix the chicken strips with soy sauce and rice vinegar. Let marinate for 10–15 minutes while you prepare the vegetables.

Prepare the Sauce: In a small bowl, combine chicken broth, sesame oil, sugar (if using), and fresh pepper. Set aside.

Cook the Chicken: Heat the oil in a large skillet or wok over medium-high heat. Add the marinated chicken and stir-fry for 2–3 minutes until lightly browned and just cooked through. Remove from the pan and set aside.

Stir-Fry the Vegetables: In the same skillet, add garlic, ginger, and onion. Stir-fry for about 1 minute until fragrant. Add the carrot, bell pepper, bamboo shoots, and water chestnuts. Stir-fry for another 2–3 minutes. Toss in the bean sprouts and cook for an additional 1–2 minutes.

Combine and Finish: Return the chicken to the skillet with the vegetables. Pour the prepared sauce over the mixture and toss to coat evenly. Stir in the cornstarch-water mixture and cook for 1–2 minutes until the sauce thickens slightly.

Serve: Garnish with spring onions and serve hot over steamed rice or noodles.