Cut beef into 1/2 inch thick slices and pound 3/8 inch thick. Marinate in soy sauce and sugar for 15 minutes to 2 hours. Add flour and egg to beef. Mix well by hand. Recipe up to this point can be made ahead.
Heat oil for deep frying. Slip beef in piece by apiece to prevent sticking together. fry til crisp. Drain on paper towels.
Remove all but 2 Tbsp. oil from wok. Stir fry chilies til black; remove. Add orange peels and sauce mixture. ( 2 Tbsp. orange juice, 2 Tbsp. dark soy sauce, 4 Tbsp. sugar and 1 Tbsp. catsup). Add 4 Tbsp. water the thicken with dissolved cornstarch. Add beef and toss. Serve with Chinese boiled rice.
Note: Peel oranges and remove as much of white part as possible. Leave to dry overnight in oven with pilot light on or for a couple of days at room temperature.