There's load of great food: don't listen to the haters. Though there was some oil stuff in the news awhile back, you don't have to fear it in most places.
For starters, you can get a stupendous variety of vegetables (particularly mushrooms) done in many styles. For some ideas there check out vegetarian-china.info/ and pics on the facebook group.
Yunnan is famed for a few things, but mostly various types of rice noodles (cold, in soup, or fried), tofu dishes, the goat's cheese known as 'rubing', and Dai cuisine. Dai cuisine is Yunnan's Tai style cuisine, which can be roughly divided in to Dehong-style and Xishuangbanna-style, which are quite different. Both feature a lot of different types of bamboo as well as palm heart (banana flower).
A good place to eat a huge variety of cheap Yunnanese food is 'Kadilan', a two-floor restaurant opposite Mandarin Books on Wenhuaxiang.
@nailer is being unfairly dismissed: they are certainly fallible. At one point they were well managed and the only game in town, and their outdoor bar had an interesting social vibe. Recently, none of these is the case (was given a bad bill to the tune of ~300% - no managers present and a subsequent complaint resulted in a less than ideal outcome, many more places are now open, and the outdoor bar is closed). Unless you are specifically seeking faux-Americana (often far better examples elsewhere) or two degrees removed faux-Mexicana, there's little reason to go there. How come French Cafe can serve a great sandwich for 24元 but Sals requires 50元 for a pretend-exoticized nibble? Certainly the business will continue, but the hey-dey is clearly gone. Romaniticizing the past aint gonna help. E-waste recycling by shipping (non carbon neutral) junk across the country? Puh-lease. Garbage processing people here recycle anyway! I applaud the ethical stance of one of the managers, but the place has frankly lost its mojo.
The listing here is wrong! Teresa's are not defunct, they are just back to being one store instead of two stores on Wenlinjie now! They are still in business, still answer on this phone number, and are still delivering! Points for consistency, it's been years! As of right now, it's 68元 for the more toppings vegetarian at the largest size. They will do thin or thick crust. Yes, it's not to everyone's taste, but I always used to find adding dried chilli powder and some extra salt brought it up to tasty. Might go for a dash of Sichuan pepper oil to spice it up this time around. (You know you've been in China too long when...)