I think Fuchsia Dunlop is well worth a look. Her online blurb states that she speaks fluent Mandarin and was trained at the Sichuan Culinary Institute, and as far as I can see, she seems to know her stuff. I've cited her on here a few times already.

Dead-tree-wise, I've only read her book on Hunan food, on which I am rather less than an expert, but I didn't see anything in there that contradicted stuff I already knew, and I found a lot of information that clarified things I'd been wondering about. Her other book covers Sichuan food — the only reason I've not read it yet is that I've already posted quite a lot about Sichuan food and I'm trying to branch out a bit :)