Marinate the Chicken:
Toss sliced chicken with soy sauce, cornstarch, and sesame oil. Let sit for 10–15 minutes while you prep other ingredients.
Make the Sauce:
In a small bowl, whisk together soy sauce, rice vinegar, oyster sauce, honey, and cornstarch slurry. Set aside.
Stir Fry the Chicken:
Heat vegetable oil in a large skillet or wok over medium-high heat. Add chicken and stir-fry for 4–5 minutes until just cooked through. Remove and set aside.
Sauté the Veggies and Mango:
In the same skillet, add a bit more oil if needed. Stir-fry onion, bell pepper, garlic, and ginger for 2–3 minutes. Add mango and cook for 1 more minute.
Combine and Cook:
Return chicken to the pan. Pour in the sauce and toss everything to coat. Cook 2–3 more minutes until the sauce thickens and everything is heated through.
Serve:
Garnish with green onions and sesame seeds. Serve hot over jasmine rice or noodles.