Don't suggest Tung Chung as it is far from Mongkok and there are no wgs there. It is barren. Waste of money to go there.
Since the OP will be in the Mongkok, he can find many places to eat from Mongkok on down to Yaumatei, then Jordan, until Tsimshatsui. In those 4 adjacent districts there are many choices of a great food from holes in the walls places to 5 star restaurants.
Plus if he does it right he won't get fat from all the eating because of all the walking and shagging he will be doing as he gets around these 4 districts. There won't be a need to take taxis, metro, or buses as everything can be reached via walking.