I just came back from a 2 week trip in California. Spent 5 days in San Francisco, which was about the right amount of time. The food there was amazing; then again, we had a relative show us around so we got to try out both the hot spots and local gems. My favourites:
Sam Tung - 1031 Irving Street - I ate there twice during the trip. This place is packed all the time. Apparently the wait time can be as long as 2 hours. They're famous for their chicken wings (I guess San Fran's version of Phnom Penh?). Dry style is more popular I think but it's still quite saucey (see photo). They kind of taste like honey garlic chicken. I'd see tables where people would order their own separate plate of chicken wings. They're awesome.
Chairman Bao - this is a food truck so they go all over the place. You can get their schedule here
http://www.facebook.com/ChairmanBao?sk=app_6009294086. They're famous for their Tender Pork Belly with Daikon bun. Get it baked!!!
Burma Superstar - I've never had Burmese food so this was something cool to try. They're famous for their Tea Leaf Salad, where you get a plate of greens, peanuts, roasted garlic, tomatoes, sunflower seeds and fermented tea leaves on a plate and the server mixes it for you. It was unlike anything I've had in Vancouver. (blurry picture but you get the gist)
Roli Roti's Porchetta Sandwich - It's another food truck and they have their schedule here
http://roliroti.com/markets/intro - We went on Thursday at the Ferry Plaza but they are also there on Saturdays. We lined up for almost 45 minutes for it but it was worth it. Definitely a must-try.
Other decent places
Sushi Bistro (several locations)
Shanghai Dumpling King (3319 Balboa Street) - hole-in-the-wall but popular with the locals
Bi-Rite Creamery (3692 18th Street) - popular joint for ice cream.. their Roasted Coconut is good