Prep the chicken: Pat the chicken dry and slice it thinly across the grain. Toss with a pinch of salt and pepper.
This helps it sear quickly and stay tender.
Make the sauce: In a small bowl, whisk soy sauce, oyster sauce, rice vinegar, honey, and chicken broth. In a separate cup, mix cornstarch with 1 tsp water to form a slurry. Set both aside.
Heat the pan: Place a large skillet or wok over medium-high heat.
Add 1 tbsp neutral oil and swirl to coat.
Sear the chicken: Add chicken in a single layer. Cook 2–3 minutes without moving, then stir and cook another 1–2 minutes until just cooked through. Transfer to a plate.
Do not overcook.
Stir-fry the vegetables: Add remaining 1 tbsp oil to the pan. Toss in zucchini, bell pepper, and the white parts of green onions. Stir-fry 2–3 minutes until zucchini is crisp-tender with some golden edges.
Add aromatics: Push veggies to the sides.
Add garlic and ginger to the center. Stir 20–30 seconds until fragrant. Avoid burning.
Combine and sauce: Return chicken and any juices to the pan.
Pour in the sauce and bring to a simmer. Stir in the cornstarch slurry and cook 30–60 seconds until the sauce thickens and coats everything.
Finish and season: Turn off heat. Stir in toasted sesame oil and red pepper flakes if using.
Taste and adjust with a splash more soy sauce, vinegar, or honey as needed.
Serve: Garnish with sesame seeds and the green parts of the green onions. Serve over rice or noodles. A squeeze of lime adds a bright finish.