For local flavors and the true PE atmosphere, head to the main market in the upper part of town, where dozens of comedores serve fresh fish and shrimp, soups and antojitos (Mexican snacks) at ridiculously cheap prices. Wander round the flower, food and craft stalls and try out some of the unusual offerings at the line of juice stalls.
'Mercado' buses (M$8) run up Av Oaxaca.