Put the duck on the chopping board and remove the fat deposits in the cavity. Cut the neck off and remove the first two wing joints, then season inside and out with salt. Put the duck in a bamboo steamer and steam over boiling water for 45 minutes, making sure not to boil the pot dry. When cool enough to handle, put on a board and remove the legs. Cut the backbone out and cut the two breasts down the middle, leaving the breastbone in place.