What are your favorite foods purchasable in stores here that require little to no preparation time?

instant noodles/3minute noodles are a good bet, especially the korean ones :p spicy fried potato vendors are on most streets (small booth or carts) and are almost alwsys pretty good - Y3/Y5 a bowl... BARGAIN! alternatively, make a little effort and 'eat well'. ;)

Beer.

Although a little hard to find here, definitely 肉夹馍(rou jia mo) also known as the chinese hamburger. There is a cafeteria style place on longxiang jie, about 20 meters down from the wenlin jie, jianshe lu intersection that serves them in the back left corner of the dining area.

卤面(lu mian) braised noodles are a good bet too, probably my favorite way to eat noddles, and a Kunming classic.

Dried tofu good

Before the food scares, I used to buy this deep fried shredded potato (rosti like) cake, sprinkled with powdered chilli.

Cao tofu (roast tofu) is reasonably safe.

Bar of Dove Chocolate, fruit and nut, or almond and coffee bean. Seriously, you can't get sick. Also, it is cheap.

I love Khong Guan biscuits with a raisin or two in each. Dry, but yummy and only 7 RMB a packet. And for those craving REAL chips (ie thick British type), the Lucky Chips stand near Paul's Shop is great.

I usually have tiny spicy fish in vacuum sealed packs, almonds, spicy peanuts with huajiao, garlic or chili roasted peas in tiny packs, Lipo cream egg biscuits, those huajiao flavoured crisps or spicy lotus root slices

Breakfast cereals, granola, etc.

almonds and fruit