Xam Yu is a relatively small and somewhat unassuming restaurant. A friend and I were bowled over by their razor clams in black beans sauce, lobster, and vegetables with soft noodles. (This latter dish was described to us as a lo mein.) They have Tsing Tao beer, which is not high on my list of great brews but is kilometers better than the Molson lager I was served in a can two nights before up the street. We both left feeling well fed and happy with our choice.
Our server was friendly and attentive.
Not being from the relevant part of the world, I can't claim that Xam Yu is 100% authentic -- though it well might be! The only evidence of authenticity that I can cite is that roughly half of the customers seemed to be speaking Cantonese (or, just possibly in some cases, Mandarin). For me, this is Chinese comfort food -- the sort of fare that I grew up with before everyone started serving General Somebody's chicken.
Highly recommended!