1. Remove sinews and tendons from the beef. Blanch for two minutes in boiling water to cover. Remove, drain and rinse under cold water. Cut into chunks.

2. Place a bamboo mat in a casserole. Spread the beef chunks on the mat. Mix together the sugar, soy sauce, rice wine, cassia bark, ginger, scallions, and all but 1 tsp of the sesame oil and pour over the beef. Add water to cover and bring to a boi over high heat. Cover, turn the heat to low and stew for six hours, checking the water level from time to time and adding more warm water if needed. When the beef is fork-tender, place it in a serving dish. Boil the sauce over high heat until thickened. Pour over the beef, sprinkle with the remaining sesame oil and serve.