Make the sauce. In a bowl, whisk soy sauce, oyster sauce (if using), vinegar, honey, cornstarch, broth, and sesame oil until smooth. Set aside.
Coat the chicken. Toss sliced chicken with cornstarch, salt, and pepper until evenly coated.
Sear the chicken. Heat 1 tablespoon oil in a large skillet or wok over medium-high heat. Add chicken in a single layer and cook 3 to 4 minutes, stirring occasionally, until mostly cooked through and lightly browned. Transfer to a plate.
Cook the veggies. Add remaining 1 tablespoon oil. Add broccoli and carrots first and stir fry 2 minutes. Add bell pepper, snap peas, and onion (if using) and cook 2 to 3 minutes more until crisp-tender.
Add garlic and ginger. Stir in garlic and ginger and cook 30 seconds, stirring constantly.
Combine and sauce. Return chicken to the pan. Pour in the sauce and toss for 30 to 60 seconds until thickened and glossy.
Serve. Serve immediately over rice or noodles with green onions, sesame seeds, and chili crisp if you like.
