Yes, San Francisco's burritos tend to be gut-busters filled with a mix of rice, refried beans, meat, cheese, guac, sour chart, even lettuce -- all a function, I presume, of competitive pressure and consumer demand, and started, I suspect, by a tiny, SF-only chain named El Faro. These thick, weighty tortilla-wrapped cylinders ain't authentic Mex, but as someone who has chowed down hundreds of such things in the course of encyclopedia years living and working in the city, I can verify that they're usually tasty (and cheap) enough to have patrons forming lines out the door at lunch and dinner. But one can also find examples of the purer form of burrito that spurns fillers other than meat and, perhaps, whole pinto beans, and that excludes all condiments other than a dollop of salsa and, only when requested, cheese. None of these latter holes-in-the-wall, however, qualify as chains -- which, frankly, adds to their authenticity, but also means I won't be finding, say, a replica of Mission Street's La Taquieria in Burney.

I'm surprised I've left Panda Express off this thread. The chain, which claims to have more than 600 locations, opened its Truckee store last year, and, well, it ain't too bad. The focus is relatively generic Chinese (Kung Pao Chicken, Sweet and Sour Pork, etc.), but the ingredients are fresh and the preparation, primarily wok-driven, is sufficiently accomplished to keep me returning every couple of months or so when I feel the need for Asian fast food. Frankly, the dishes at Panda Express put those of the other two Chinese restaurants in town to shame.

Of course, for a really superior Chinese-cuisine chain, there's Henry's Hunan, which has three or four or five storefronts in San Francisco. But that's it. One hopes that at some point they'll expand into the hinterland....