1/2 pound chicken breast, sliced about 1/8 inch thick
1/4 teaspoon salt
1/4 teaspoon sugar
1/8 teaspoon ground white pepper
1/2 teaspoon Shaoxing wine
1/2 teaspoon soy sauce
1 teaspoon plus 3 tablespoons vegetable oil, divided
1/2 teaspoon cornstarch
10 thin slices julienned ginger, plus one 1/4-inch-thick slice
4 scallions, cut into 2-inch segments
1 medium onion, sliced
3 medium cloves garlic, finely minced (about 1 tablespoon)
Steamed rice, for serving