Welcome to our city!! Glad that you enjoyed the dim sum very much. In Hong Kong, tableware washing is a tradition of "yum cha" (飲茶). The old days HK, overall hygiene is not good enough and people used to rinse tableware in hot tea or water before having meal in the morning because tableware are set on the table the night before. So, next time when the staff gives you a larger bowl before ordering, you know you can rinse the tableware, however, it might not be common among high-class restaurants. see u next time in HK😊