Mysterious Edible Flower

The produce at Hong Kong Market on the Westbank is always interesting, but after five years of shopping there, I thought we'd seen most of the variety they had to offer. However, neither Chris nor I could identify these flower buds (labeled "Bong Sua Dua," but I've think I've seen that on other produce). From the shape and some Google images, I'm thinking they might be pea flowers. Can anyone confirm this and/or offer details on how they are used?