Make the sauce: Whisk the cornstarch into the chicken broth until smooth, then whisk in the soy sauce, oyster sauce, honey, sesame oil, garlic, and ginger. Set aside.
Preheat the Blackstone to medium-high (375–400°F) for 8–10 minutes.
Prep the chicken and season with salt and pepper; chop all vegetables and keep them nearby.
Sear the chicken: Add 1 Tbsp oil, spread the chicken in a single layer, and sear undisturbed 2–3 minutes. Toss and cook 3–4 minutes more until browned and 165°F. Set aside.
Cook the vegetables: Add a little oil, then carrots and broccoli; cook 2 minutes. Add bell peppers and snow peas; cook 2–3 minutes until tender-crisp.
Combine: Return the chicken to the griddle. Re-whisk the sauce, pour it over everything, and toss 1–2 minutes until glossy and thickened.
Serve: Garnish with scallions and sesame seeds. Serve hot over rice or noodles.