Slice pork belly into 5cm wide and 1cm thick sections. Marinade with all the seasonings for at least 1 hour
Coat the pork belly with jenrofen powder/rice powder and leave it aside
Prepare a 21.5cm wide bamboo steamer or similar size heat proof bowl and line it with baking paper
Place a layer of sweet potato on the bottom of the bamboo steamer then layer the rest of the bamboo steamer with the pork belly. Sprinkle some extra jenrofen powder on top and cover with the bamboo steamer lid
Place a steam rack into the wok and pour 1 litre of water into the wok. Boil the water first then put step 4 on the rack and cover everything with the wok lid. Turn the gas power to medium and steam it for 2 hours. Check occasionally but make sure there’s always water in the bottom of the wok