Despite the relatively poor status of Rio, there is some outstanding food to be found there. Like much of the world outside the US, there are almost no preservatives used in their food, and therefore most things have a fresh taste that is foreign to lots of foods at home that taste relatively bland by comparison.
While you can find a variety of restaurants there, even the bottom of the line ones seem to take great pride in everything they serve. In fact owners almost have a competitive feel to the presentations they serve. The picture above is from an open market where shoppers do their almost daily shopping. Like Europe, it is much more popular to buy food fresh every day than to store it for weeks at a time in big refrigerators.