I highly recommended two outlets in the Food Court located at the 99 Ranch Market in Rosemead at the junction of Garvey and San Gabriel.
In the right hand corner is an outlet called Harlam which serves Cantonese style noodles, porridge, fried rice and more. The Wonton is delicious. The first time I was there, it was by chance, and I ordered the beef stew and wonton noodle. I was blown away! Today, I returned and had the Fishball noodles and Dried Shrimp Cheung Fun (steamed noodle). It's the best I've had in Los Angeles in the last 10 years.
There is another outlet, I can't remember the name, but it serves cuisine the Heilongjiang province in China. They serve great dumplings and potstickers. The beef noodles are a blast... and definitely has a Russian influence.
There you have it.. Northern and Southern Chinese in one food court.