Seafood is typical of the city. One of the best restaurants is restaurant Safari. It's located in the neighborhood "El Rastro". Safari is a nice, warm, cozy restaurant that is right beside the beach. There you can order traditional plates like tapado, camarones a la plancha, ceviche and many others.Another typical Garifuna-plate is rice'n beans, which has rice, beans, coconut cream and meat.
Other restaurants are "El Castillo", "Fogón Porteño", "Pepin Burger","Restaurante y Cafeterìa MAXIM" and "Doña MarÃa" and some others that have special things like churrascos or tortillas de harina.
If you like Cuban food, you can go to "La Habana Vieja". This restaurant is located on 8th avenue between 7th and 6th streets. You can eat the best pieces of meat in there.
If you want to try a typical of the entire country; you can go to "Pollo Campero" Country Chicken It's located in 8th street and 7th avenue, next to the Central Market. This is an international chain of restaurants like Kentucky Fried Chicken, but has the special Guatemalan flavour.
If what you are looking for is for 1st class cuisine, go to the Mar Brissa hotel or to Amatique Bay hotel. The finest restaurants in town. Both of them are a little far away form downtown, but is very easy to get to them.
For sure you should try the fresh fruits that are sold in the local market. Papaya, mango, melon, pineapple and many others like you've never eaten before. You should also taste the 'licuados', juices and milkshakes that refreshes very well in the tropical heat.