Let Us Tour China
When I was a kid my parents took us around the world by trying every ethnic restaurant they would find in Los Angeles. Now I am trying to do something similar by putting together a list of select references for a tour of the Chinese regions. I know I could search the board, but with the rate that restaurants close, and chefs move, that may not be too accurate. I would appreciate a list of the best restaurants in the San Gabriel Valley for each of the following regions:
I know of no Hakka restaurants in the L.A. area. Despite the fact that Fujianese dominate New York Chinatown, and indeed probably run a large portion of the Chinese restaurants east of the Mississippi, all I can think of here is Foo Chow in Chinatown. (Many Fujianese are not documented and would have to bus their way here from New York, which is probably not worth the effort.) A few places do serve Fujianese fish balls, such as the restaurant upstairs from the Monterey Park Hong Kong Supermarket.
Instead of listing the different regions, I think your idea might be better served by listing notable dishes of each region -- e.g. XLB (Shanghai), dumplings (Beijing), lamb (Islamic), etc.
It's really difficult to say that one restaurant is indicative of one regional type of cuisine. Take for example what you have listed as Guangdon (or Cantonese), lots and lots of restaurants in SGV will serve Cantonese type cuisine, but I wouldn't necessarily pigeon-hole them as purely a Cantonese restaurant.
And many aspects of Guandong food encompass Fujianese flavors and cooking techniques, so it's really rather hard to draw carefully delineated labels for Chinese restaurants.
You can have very good Sichuan AND Yunnan at Hacienda Heights' Yunnan Garden.
Islamic: China Islamic (though I prefer Mas Islamic Chinese in Anaheim)
Guangdong: Oh god take your pick of any of the seafood extravaganzas. Sea Harbour, for instance.
Fujian: No native Fujian as far as I know, but Temple City has Seafood Village which is Chaozhou (technically Guangdong province but adjacent to Fujian's Zhangzhou district). Occasionally you'll find a place that makes fotiaoqiang but there's a distinct lack of wine-cooked dishes and yeast-rice and suchlike.
Shanghai -- I'm not sure these days. I'd have said Green Village but it's closed. Maybe Mei Long?