In a small bowl, whisk 4 tablespoons oil, vinegar, sugar, celery seed and salt until sugar is dissolved; set aside. , In a large skillet, saute the cabbage, carrots and onions in remaining oil for 15-16 minutes or until crisp-tender. Stir in vinegar-oil mixture and corned beef. Cover and simmer for 10 minutes or until heated through. If desired, serve with rice.