preheat oil to 375F
Cut the beef into 1"x1" pieces.
Place beef in a tupperware container, add 1 tbsp of soy sauce, cover and shake vigorously to coat
Add corn starch to the beef and shake some more to coat thoroughly.
In a medium mixing bowl zest half the orange peel, then halve the orange and juice it into the bowl. Optionally use a vegetable peeler to get some peel strips for garnish. Add 2 tbsp soy sauce, hoisin sauce, vinegar, garlic, ginger, red pepper flakes. Whisk to combine.
Deep fry the beef in the oil for 3 minutes, at the same time bring the sauce to a boil in a wok. When the beef is done, drain and add to the sauce. Continue to cook on high for another 3 minutes, tossing regularly to coat. Serve over rice.