Combine 2 tablespoons cornstarch and 1 tablespoons soy sauce in small bowl; stir in chicken. Let stand 30 minutes.
Meanwhile, combine sugar, 2-1/2 teaspoons cornstarch, lemon peel and juice, remaining 3 tablespoons soy sauce and 1/4 cup water.
Heat oil in hot wok over high heat, Or if using skillet, heat oil over medium-high heat. Add chicken and green onions; stir-fry 3 minutes. Remove.
Reduce heat to medium-high. Pour soy sauce mixture into wok; bring to boil. Cook, stirring constantly, 1 minute. Add chicken and green onions, stirring to coat all pieces well with sauce. Serve immediately.