Not sure if this has been mentioned already, but the famous Shanghai Restaurant in Oakland has opened a branch in San Mateo.
According to my Shanghainese friends, this is probably the most authentic Shanghainese restaurant you can find in the Bay Area.
I went last weekend and the restaurant was still packed at 2:30pm. Long wait and very slow service because there were only 2 waiters serving the whole restaurant.
Food was OK - the soy milk is probably the best I've had in a Bay Area Shanghainese restaurant. I also had the xiao long bao, which is ok. I'm picky with xiao long bao and so far haven't had any good ones in the Bay Area. I would prefer Din Tai Fong in LA or Joe's Shanghai (Flushing branch) in NY. We also had the smoked fish with noodles and the soup base was good for the noodles. I ordered a cold dish of cucumber which was ok, nothing remarkable. I need to order more things in the future to give this restaurant a true review.
I wouldn't mind coming here more often if I didn't have to wait for such a long time. Also, the waiters were pretty unattentive because we asked 3 times before they finally took our order. Our waiter pretended not to see us because he was so busy trying to deliver food to other tables.
I would prefer to go to the Oakland branch because I never see such a crowd during lunch (I go there on the weekday because I work in East Bay) and the service was better. I can't really conmpare the food in the Oakland branch vs. San Mateo because I didn't order the same things. The only thing I could compare would probably be the xiao long bao. I think Oakland's version was better. However, it could be because the San Mateo branch was so busy that they screwed up the steaming time. I know that the Oakland branch does not make their own xiao long bao - I witnessed a delivery of xiao long bao to the restaurant when I was there for lunch one day.
Anyways, for those Shanghainese food fans, the address is:
105 W 25th Avenue