What are alkaline rice dumplings, the Dragon Boat Festival sweet treat loved by an empress?

Alkaline rice dumplings, a sweet treat often enjoyed with red bean paste, peanut sauce or honey, can be an acquired taste for those in Hong Kong celebrating the Tuen Ng Festival, or Dragon Boat Festival.
This is because, in China, rice dumplings are sweet in the north and savoury in the south – or so the saying goes.

In Hong Kong, glutinous rice dumplings stuffed with pork, salted egg yolk, mung beans and mushrooms are more common.
Historical records reveal that alkaline dumplings with sweetened...