Maybe you have tried this before but this is something that is worthy to promote a little bit... :-P
Shake'em Buns, a burger restaurant in Causeway Bay, introduced by my dear friend Annabelle a while back... There are lots of burger restaurant here in HK nowadays and so far, I like Triple O the most (becoz of the good old days I had in Vancouver BC a long while back)... but this one, after I tried it, OMG, the burger is just too good to be true and I have changed my mind since then. It's so juicy and yet not greasy... I added an egg to the burger for HK$7 and it just made it even better. Finished it very quickly.... and had my hands full of source and the juice from the burger itself (sounds better not to eat this in front your girl... hahahaha)..... the burger I ordered was Missionary + an egg... :-)
4 stars was the rating I gave... out of five...
It's on Hoi Ping Road, the road just opposite of LV in Causeway Bay in case you do not know.
Missionary + Egg
Order original fries with a burger, you save HK$6 and all you have to pay is HK$12 instead of the original HK$18. But my recommendation is to order the other one... it's HK$30 something but it looks, smells, and tastes far better. Drink is a bit expensive but you will probably need something to drink.... tho choices are quite limited to softdrinks or beers...