Marinate chicken (aka "velveting"): Cut the chicken thighs against the grain into 1-inch thick pieces. In a bowl, combine the sliced chicken with the all the marinade ingredients. Cover and marinate for 20 minutes at room temperature.
Prep: Meanwhile, prep all the vegetables and stir fry ingredients. Having everything ready is important because once you start cooking, everything happens quickly over high heat.
Make the stir fry sauce: In a bowl, dissolve the chicken broth with cornstarch. Then, add the light soy sauce, dark soy sauce, oyster sauce, shaoxing wine, and granulated sugar and mix until evenly combined. Tip: Cornstarch dissolves best with room temperature liquids, so make sure the broth is at room temp.
Cook chicken: Heat a large wok or skillet over HIGH heat and add a few generous drizzles of vegetable oil. Once hot, add the chicken and cook until fully cooked and golden brown, about 4-5 minutes. Transfer to a plate and set aside. Tip: To get a golden crust, cook undisturbed on one side first until golden (about 3 minutes) before stir-frying it to cook the chicken fully.
Add vegetables and aromatics: In the same pan, add a few more drizzles of oil as needed, and then sauté onions, celery, and red bell peppers for about 2 minutes until crisp tender. Push them to the side of the pan, add a bit more oil then sauté garlic and ginger until fragrant, another 30-45 seconds.
Combine and add sauce: Return the chicken to the wok. Give the sauce a quick stir again and then gradually add it into the stir fry (adjust the amount to taste). Cook for 1-2 more minutes until the sauce is thickened, stirring.
If you’d like, add another pinch of sugar to balance out the savory flavor profile, but I didn’t find this necessary. Serve immediately with rice or your favorite sides. Enjoy!