Beat egg white lightly in bowl. Add 1 tsp cornstarch, salt, sesame oil and dash pepper. Mix and add chicken. Marinate 30 minutes.
Combine 1 teaspoons cornstarch with chicken stock, sugar and dash pepper, mix and set aside.
Heat 2 Tbs. oil in wok. Add zucchini and stir-fry until tender-crisp, 3-5 minutes. Remove from wok and cover to keep warm. Add 1/4 cup oil to wok and heat. Add chicken and stir-fry until chicken is about done, 4-5 minutes. Return zucchini to wok. Stir chicken stock and add to wok, stir-frying until sauce thickens.