Best divey joints in Little Haiti, Little Havana
I second Chez Rosie & Chef Creole, try the fried shrimp or the oxtail at Chez Rosie.
Yambo on 1643 SW 1st street has cheap Nicaraguan good & for El Salvador's national dish (pupusas) try Altakat on SW 8th & 32nd Avenue, surprisinly they have valet on weekends. You can try the national dish of Honduras (baleadas) at Honduras Maya on 69 NW 27th avenue. All of these are affordable options. Have fun exploring.
In Little Havana:
El Nuevo Siglo. Calle Ocho and SW 13th Ave. A grocery store with a lunch counter that has some of the best cuban food in Miami. Most expensive item is around $8 with MANY items being in the $5.50 - $6 range. Menu changes daily.
Good peruvian (slightly more expensive) at.. well, poop, the name escapes me, but it is about 3 doors west of SW 16th Avenue on Calle Ocho on the south side of the street.
GREAT, AWESOME mexican at Mi Rinconcito Mexicano on Calle Ocho at 20th Avenue (north side of the street).
Good Nicaraguan at La Esquina Nica, 16th and Flager -- try the repocheta -- a deep fried white cheese in a fried thick-style nicaraguan tortilla smothered with lightly pickled cabbage and "crema" (nicaraguan style sour cream).. amazingly tasty for $3 For an unusual drink, try the pitahaya -- dragonfruit drink or the cacao con leche (spiced chocolate milk)
Decent uruguayan at Con Tutto on Calle Ocho between 13th Court and 14th Avenue
There is good Guatemalan at Antigua, Guatemala -- just west of 27th Avenue on Flagler. Try a pupusa --- tasty filled corn tortillas (the tortilla is cooked with the filling totally encapsulated).. typically served with encurtido (spicy pickled cabbage slaw).
Little Haiti is definitely an area to be careful around. That being said, Chez Rosie and Chef Creole are both very very good. I'd especially recommend the seafood at Chef Creole. Delicious, meaty conch fritters, succulent shrimp. It's an open air space with some benches you can sit at or take out. Chez Rosie is smaller, all white inside and has pretty good meat and chicken.