The local specialty is fried fish — snapper, sea bass, or whatever came in fresh — served with tostones (fried plantain), rice, and salad. The beachfront restaurants along Calle Duarte and the sand itself are the places to eat it. Prices are very reasonable by Caribbean standards, and quality is generally good.
Most beach vendors sell seafood caught the same day. If you want a proper sit-down meal away from the beach bustle, the residential streets behind the main strip have a handful of small Dominican restaurants (comedores) where locals eat. These are cheaper and more authentic than the tourist-facing places on the waterfront.