In a medium bowl, combine the chicken, soy sauce, Shaoxing wine, and cornstarch. Mix gently until the chicken is evenly coated. Let it marinate for 10-15 minutes while you prepare the sauce.
In a small bowl, whisk together all sauce ingredients until the sugar and cornstarch are dissolved. Set aside.
Heat 1 tablespoon of oil in a large skillet over medium-high heat. Add the marinated chicken, spreading it into a single layer. Sear undisturbed for about 1 minute, then flip and cook for another 30 seconds until lightly browned but not fully cooked through. Remove the chicken from the skillet and set it aside.
In the same skillet, heat the remaining oil. Add ginger and garlic, stirring until fragrant, about 15 seconds.
Add chopped onion and bell peppers. Stir-fry for 20 seconds until they begin to soften but still retain some crunch.
Give the sauce mixture a quick stir and pour it into the skillet. Stir constantly as the sauce thickens to coat the back of a spoon, about 10 seconds.
Return the seared chicken to the skillet and toss to coat everything evenly with the sauce. Cook for another 1-2 minutes until the chicken is fully cooked and the flavors have melded.
Turn off the heat and immediately transfer to a serving plate to prevent overcooking. Serve hot with rice or noodles of your choice.