For a full sit-down meal, you can try local Chiapan food at Las Pichanchas, Av. Central Oriente 837 (tel. 961/612-5351). It's festively decorated and pretty to look at. The emphasis is on meat, with several heavy dishes on the menu. I would recommend the filete simojovel (a thin steak in a not-spicy chile sauce) or the comida grande, which is beef in a pumpkin-seed sauce. Eating here is a cultural experience, but I usually head over to the Flamingo, 1 Poniente 168, just off Avenida Central (tel. 961/612-0922), which serves standard Mexican dishes: enchiladas, mole, roast chicken. The restaurant is owned by a Spaniard, who also owns a decent steakhouse called El Asador Castellano, which is on the west side of town. Take a taxi.
If all you want is tacos, there are several good places around the plaza called El Parque de la Marimba. This plaza has free marimba music nightly and is enjoyable. There you'll find a couple of local taco restaurants bordering the plaza, Parrilla Suiza and El Fogón Norteño. Both have good grilled tacos. The Parque de la Marimba is on Avenida Central Poniente, 8 blocks west of the main square.
