For a quick, cheap and filling lunch in Wanchai, my go-to place is Red Moment Coffee Express — a hole-in-the-wall shop right underneath the bridge going to the Immigration Building close to Gloucester Road.
They serve coffee, tea, sandwiches and pasta, as well as my default desk lunch — a Borsch-like chunky vegetable soup during lunch hours that’s made daily with cabbage, celery, carrots, and tomato. For HK$35 you can get a big tub of that soup with fusilli pasta and two toppings of your choice (including mushrooms, corn, tuna, egg, imitation crab, turkey slices, ham, etc), PLUS a coffee or tea.
Since I like to keep things light (and I don’t eat meat now), I usually go with two eggs (1 + 1 minus the yolk), no pasta, and extra veg (they are more than happy to oblige). Without the coffee/tea, the soup is just HK$28 and quite filling already.
Try it out if you’re in the area! Their coffee’s not half bad either, and many people say it’s even better than Starbucks, Habitu and Pacific Coffee which is just around the corner.