Heat oil in a skillet or wok over medium heat; add chicken, sprinkle with garlic salt. Cook chicken until no longer pink, stirring occasionally, 3-5 minutes.
In a small bowl, combine the orange juice, soy sauce, cornstarch and ground ginger. Pour over chicken. Bring to a boil; cook and stir until thickened, 1 minute. Add orange segments; stir gently. Sprinkle with green onions. Serve with rice. If desired, garnish with chopped walnuts and red pepper flakes.