In a bowl, toss sliced chicken with 2 tablespoons cornstarch until coated.
Whisk all stir-fry sauce ingredients together and set aside.
Heat 1 tablespoon oil in a large skillet or wok over high heat.
Add chicken in a single layer and cook until golden and cooked through. Remove and set aside.
Add remaining oil, then stir-fry vegetables until tender-crisp.
Add garlic and ginger; cook 30 seconds until fragrant.
Return chicken to the pan. Pour in sauce and toss until thickened and glossy.
Remove from heat and serve immediately.