The one big problem with Chinese food is that it ain't pretty. Taking pictures of them don't do the food justice cus it's always one big stir fry. Unlike Western food where every food item is a standalone piece of art (or not), Chinese food is made to share and rarely presents a good photo opportunity unless you take the picture of the whole thing.
So, no pictures in this post.
Central - Hong Kong's central business hub has all kinds of lunch food that attracts all sorts of crowds. Restaurant name in bold.
兰芳园 has the best 奶茶 (milk tea) in Hong Kong. Iced or hot, you have to try it. Across for the store is 龙记 which has pretty good BBQ pork. Nearby next to the escalator is 蛇王芬 and they serve a kick ass snake soup. Also on the escalator route is the 豆腐花 (Soft and sweet tofu) place - it is a simple street side stall, no name as far as I can tell - where people sit on the side of the street and enjoy their dessert. 2nd best in Hong Kong by my count (#1 is in Lamma Island). On Wellington Street are one of the world's "most concentrated with good food" place: 镛记 is an award winning restaurant with 烧鹅 (roast goose) and 皮蛋 (duck egg) as their signature dishes. The roast goose has mixed results depending on the chef, but the duck egg is a must eat. Best in the world. Wonton noodles from 沾仔記 and their rivals 麥奀 (former beats latter) are awesome and dirt cheap. Also on Wellington Street is 莲香, one of the most old-school restaurants in Hong Kong. The service is suspect, but the food is proven. Get the 霸王鸭 while they still last in the early evening. One street up from 莲香 is the super good 九记. You MUST try the 牛腩伊面 (Beef brisket in Yi noodles) and the 牛爽腩 (I have no translation). Some like the curry beef brisket, but I find it to be too strong. Also super good is 勝香園 next to 九记, also serving a similar flair of cheap good canton food. One street down from Wellington is Stanley Street, where 陆羽 is. Best freshly made dim sum you can find in Hong Kong. They change their menu every week starting Saturday morning depending on what ingredients are best. So my advice is to go on saturday morning and order every dim sum you have never heard of before. Also on Stanley street is 南记, which is a chain serving decent spicy noodles for a reasonable price. Across from 南记 and the escalators, you can find a few 大排挡 which serves basic canton dishes that is very very good and very very cheap (hygiene not included).
Excuse me... need to wipe the drool off my face.
Other noteworthy restaurants: 小南国 (Shanghai food), 金華 (BBQ Pork), 黃枝記 (Congee), 翠華 (Beef noodel, currey beef brisket, fish ball, very yummy milk and butter bun), The Frying Pan (All day breakfast)... oh my god, there's so many... I have to stop.
In the past, I've covered some up scale restaurants such as Caprice, Zuma and H One. H One's brother, Harlans, serves a surprisingly good burger at HKD180 too. WaterMark, out in the pier, has a decent brunch buffet with a spectacular view of the harbour.