Here are two things that you need to try in this city.

1. I call it Heart Attack Toast ($5) or cube toast with condensed milk as it appears on the menu.  Imagine a cube of toast, scored in the middle, with a chunk of butter on top and then condensed milk poured over top.   Not the food to eat if you are watching your fat intake but you can get the ligher version which has honey instead of condensed milk but it still comes with the slab of butter melting on top.
Available at most HK Cafes but this one was from I Cafe.

I Cafe
2525 Heather Street
I Cafe on Urbanspoon

2. Chicken salad ($15)- cold hand pulled chicken, pickled vegetables, jelly fish, some hot sauce and crispy noodles.  A fantastic array of textures and flavours

Koon Bo
5682 Fraser Street
Koon Bo Restaurant on Urbanspoon