Cut chicken into 1 1/2 inch cubes. Lightly toss with cornstarch in bag to coat. Heat oil in skillet or wok; stir-fry chicken and garlic until lightly browned. Add soy sauce, vinegar, sugar and water. Cover and cook 3 minutes or until chicken is cooked through. Add green onions and cayenne; cook uncovered about 2 minutes longer. 221 calories per serving.