One thing when you come to Hong Kong is to eat street food. One thing that you should not miss as a snack in Hong Kong is "Waffle Ball" or "Gai-Daan-Jai" which Gai-Daan means Egg !!!
It's a waffle in the shape of egg -- crispy outside and soften inside (like eating waffle). You can find it easily in traffic area where the shopper is -- mostly at street food area such as : Causeway Bay (where I took these below pictures)
or the famous one in Kowloon (on Granville Road) where long queue always happened ... and the shop owner put his advertisement and article on as the billboard above the shop including kiosk area. See the left picture