Prep the chicken: Thinly slice the chicken breast. Toss with 1 tablespoon soy sauce and 1 tablespoon cornstarch.
Set aside while you prep the vegetables.
Make the sauce: In a small bowl, whisk together soy sauce, oyster sauce, rice vinegar, honey, sesame oil, red pepper flakes, chicken broth, and 2 teaspoons cornstarch. Set aside.
Heat the pan: Place a large skillet or wok over medium-high heat. Add 1 tablespoon oil and swirl to coat.
Sear the chicken: Add 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 the veggies: Add the remaining 1 tablespoon oil to the pan. Add bell pepper, broccoli, carrot, zucchini, and snap peas.
Stir-fry 3–4 minutes until crisp-tender.
Add aromatics: Push veggies to the sides. Add garlic, ginger, and the white parts of the green onions to the center. Cook 30 seconds until fragrant.
Combine and sauce: Return chicken to the pan.
Give the sauce a quick stir (cornstarch settles), then pour it in. Toss everything for 1–2 minutes until the sauce thickens and coats the stir fry.
Finish and serve: Turn off the heat. Sprinkle with the green parts of the onions and sesame seeds.
Serve over warm rice or noodles with lime wedges if you like.