1. **Velvet the Chicken:** In a medium bowl, combine the chicken pieces with 1 tbsp soy sauce, 1 tsp sesame oil, 1 tbsp Shaoxing wine, 1 tbsp cornstarch, and the egg white. Mix thoroughly until all chicken is evenly coated. Let marinate for at least 15-20 minutes at room temperature, or up to 30 minutes in the refrigerator. 2. **Cook Velveted Chicken:** Heat 1 tablespoon of vegetable oil in a large wok or skillet over medium-high heat. Add the velveted chicken in a single layer, spreading it out. Cook for 2-3 minutes until it's about 80% cooked through (lightly browned but still a little pink inside). Remove the chicken from the wok and set aside. 3. **Stir-fry Vegetables:** Add the remaining 1 tablespoon of oil to the wok. Add the sliced mushrooms and bell pepper. Stir-fry for 3-4 minutes until they are tender-crisp. Add the minced garlic and grated ginger, stir-fry for another 30 seconds until fragrant. 4. **Prepare Stir-fry Sauce:** While the vegetables cook, whisk together 2 tbsp soy sauce, oyster sauce, sugar, white pepper, 2 tbsp water or chicken broth, and 1 tsp cornstarch in a small bowl until smooth. 5. **Combine and Finish:** Return the pre-cooked chicken to the wok with the vegetables. Pour the prepared stir-fry sauce over everything. Stir constantly for 1-2 minutes until the sauce thickens and evenly coats the chicken and vegetables, and the chicken is fully cooked. 6. **Serve:** Remove from heat and serve immediately over steamed rice.