The food here is nothing if not eclectic. Expect to find sushi bars, Italian restaurants, and German biergartenssitting alongside restaurants selling typical Brazilian cuisine. Coastal towns serve a large selection of fresh seafood, and most have a local specialty that's worth trying. Beachfront restaurants, especially the ubiquitous baracas (kiosks), can be a pleasant surprise and most will bring food and drink right up to your chosen spot on the sands.
Paraty and Búzios have excellent restaurants serving international cuisine. During high season they fill up beginning at 10 pm and may not close until after sunrise. Restaurants in Petrópolis and Teresópolis serve European cuisine and comida mineira, the hearty, meaty fare from Minas Gerais. Generally, dinner starts at seven and restaurants close around midnight.
To be on the safe side, don't buy seafood from venders strolling along the beach. Be especially careful about the oysters in Búzios and Cabo Frio, which may not be as fresh as the vendor claims.