Slice the chicken thin against the grain. Toss it with the egg white, 1 tbsp cornstarch, the Shaoxing wine, and a pinch of salt until every piece is coated. Chill for 15 minutes while you prep everything else.
Whisk together the soy sauce, oyster sauce, sugar, sesame oil, and chicken stock. In a small cup, stir the 1 tsp cornstarch into 1 tbsp cold water to make a slurry.
Heat 1 tbsp of the oil in a wok or large skillet over high heat until it shimmers. Add half the chicken in a single layer, sear undisturbed for 1 minute, then toss until just cooked through, about 2 minutes total. Move it to a plate and repeat with the second batch.
Add the last splash of oil to the hot pan, then the ginger, scallion whites, and garlic. Stir fry for about 45 seconds, until fragrant but not browned.
Pour in the sauce and bring it to a simmer. Stir in the cornstarch slurry and cook until glossy, about 30 seconds.
Return the chicken and any resting juices to the pan, add the scallion greens, and toss to coat. Cook 1 minute more, then serve hot.