In lg skillet, heat oil over med-high heat. Brown the beef until just cooked. Don't overcook the beef, or it will be dry and chewy. Add reserved mandarin orange liquid, soy sauce, honey, garlic and ginger.
Mix well. Reduce heat to medium. Cover, cook 15 mins, or until beef is tender. Stir occasionally. In small bowl, combine 2 tbsp liquid from skillet and cornstarch. Add to skillet. Add oranges to skillet. Stir until sauce thickens.