I almost missed one iconic Hong Kong dish ... but was luckily reminded. Won ton noodle soup (Wan Tan Min) is a simplistic affair, drawing its appeal from a the perfect execution of the three ingredients: Won tons (purely made with shrimp), super-thin egg noddles that are barely cooked (and reamin crunchy, almost like shirataki noodles) and a lightly seasoned fish broth (from dried fish/shrimps, that sometimes has undertones of cured pork products). Occasionally gai lan or gau coi (garlic chives) are added.
For lunch I usually go to the Midlevels, which stretch uphill from Central along the slopes of Victoria peak. Alas, you don't have to climb thanks to the roofed midlevels escalator, that conveniently transports you via several stages up the hill.
While walking/riding up, you have good views over the streets and into the neigbouring buildings ...
Mak's Noodles is similar iconic, being located in Wellington street since somewhen in the 50's (the bottom of the picture).
Two chefs are happily working in the front kitchen of the shop, dishing out houndreds of won ton soups in the next two hours or so ...
Menu is simple and cosists of the won ton soup and its varaitions (with brisket, additional pork dumplings etc.). Alternatively, they offer all dishes "dry", e.g. without the broth but then accompanied by a brown sauce (if desired).
I took the classic (40 HKD). Very hot, noodles very crunchy, won ton slippery and soft and a very flavorful broth.
In order to make sure I get a seat I went early (11.30h) and I was successful. About thirty minutes later you would need to queue.
Strolling back to office you can take the little cobble stone alley downhill, where you can pick up daily necessities from little electric fans over second hand books to your next scary Halloween mask 
