While many of the foods sold in the streets of Lahore and other cities look quite tempting; they can be a pain once you digest them. I would warn against eating from street vendors unless your stomach is really used to that time of food, since it tends to be pretty unsanitary.
This applies to all of Pakistan I suppose.
Fondest memory: When I was a kid, one vendor came by my grandfathers house selling some salty breaded food. I ran inside to get some money, but then he was gone. I went looking for him, and got lost in a "gujar bustee". It was scary at the time, but it's a good memory.