In a bowl, combine ingredients for velveting: egg white, Chinese cooking wine, 1 tablespoon of the oil. cornstarch and salt. Whisk together until well-blended and frothy. Add chicken and marinate in the refrigerator for about 30 minutes. Drain chicken well.
In a pot over high heat, combine about 2-inches deep of water and 1 tablespoon of oil. Bring to a boil. Reduce heat to medium low and immediately add chicken, stirring to disperse. Bring water back to a gentle simmer and once it's barely bubbling, continue to cook chicken for about 1 minute, stirring occasionally. With a slotted spoon, remove chicken from pot and drain well. Keep warm and set aside.
In a bowl, combine stir-fry sauce: oyster sauce, chicken broth, soy sauce, brown sugar, sesame oil, cornstarch and pepper. Whisk until well-blended and cornstarch is dispersed. Set aside.
In a wok or wide pan over high heat, heat the 2 tablespoons of oil. Add garlic and ginger and cook, stirring regularly, for about 30 seconds or until aromatic.
Add green beans and cook, stirring regularly, until wrinkled.
Add stir-fry sauce mixture and cook, stirring quickly, for about 1 minute or until thickened.
Add chicken and cook, stirring regularly, for about 2 to 3 minutes or until chicken is heated through. Serve hot.