Why would you be posting about a "lettuce shop" with veggies? In Central there are a handful of places selling fresh, organic, delicious lettuce, and, surprisingly, since they are veggie shops, they sell other vegetables, too, like tomatoes, carrots, (local) eggplants. There is even an organic stall in the Sai Ying Pun wet market. It hardly seems news to me to find out about a shop that sells lettuce, as it's one of the easiest things to find in HK. Did you know there is an organic, local farmers market at the Star Ferry Pier on Sundays? Plenty of lettuce there, too.
As for dressing: just get good olive oil, and you can mix that with a little bit of fresh lemon juice (there are lots of fruit stands that sell lemons in HK!) or balsamic vinegar, salt + pepper, + fresh or dried herbs. Hardly any need for the extra, mysterious calories in some pre-made dressing. Give it a try!
Kimwy, I envy your parsley!