Add 3 tablespoons of cooking oil to a large wok over high heat. Once it begins to roll smoke add in the beef and immediately move it up the sides of the pan so that all of the pieces can get cooked.
Stir-fry for 2 to 3 minutes and set aside. Add 3 tablespoons of cooking oil to the wok and return it to the burner over high heat until it rolls smoke again.