There quite a few restaurants over on the Centennial Campus of HKU - more so than on the Main Campus, at least. Grove on LG/F is great for a quick meal - there's a good variety of sandwiches and salad here, which is what I normally go for. During lunch times, the lines get pretty insane and you do have to wait for quite a while. You're better off getting something to takeaway than waiting for a table here, because it can be quite loud inside too.
I normally get the normal Caesar salad here. It's only $20, which seems inexpensive, but the portion is really quite small. I'm not a quick eater, and I can finish this in ten minutes or less. The small portion size makes it more suitable as an appetizer, in my opinion! The salad has some cheese, bacon and croutons, and salad dressing is placed in a separate small container. The croutons are terrible - they're practically just wheat bread and are not crispy in the least. I'm not sure what kind of dressing it is that accompanies the salad, but I quite like it as it is thick but refreshing. They also have chicken career salad which has a few slices of chicken. The chicken is actually quite tender surprisingly. If you're not one for salad, there are some sandwiches too - just your basic fare like ham and cheese and tuna mayo.
After lunch hours, Grove gets significantly quieter and you'll be able to find a table inside - but if not, just take away. There're plenty of couches and benches around Centennial Campus for you to sit on and eat anyway! read more