Mostly on the weekends restaurants (and sometimes individuals) will set up grills on the side of the road and roast kid goats, chicken, sausages, etc.
Not exactly haute cuisine, but at least you see how and where it's being cooked, and the price is usually right.
When travel trought Mexico you can taste a variety of natural fresh water, most common are, lemonade, jamaica (red colored water made from saborizated flowers), orchata (white colored water made from rice and cinnamon) and tamarindo (brown colored).
These fresh water are sold everywhere even in streets but try it only in restaurants or hotels by safety.
Every time you visit Mexico, in any region, you can enjoy the tradicionals Tamales, made with corn, beef, chicken or beans envolved in a corn sheet.