If you are planning to come to Brazil, without going to Salvador, you might consider having dinner at Yemanjá. This restaurant offers you typical food from this northeastern area of Brazil, but right there, very close to the main hotels in Rio.
The food is very spicy and mostly with lots of fish, shrimps, coconut milk and palm oil. Fresh vegetables and rice to complete your exotic meal.
The place is very much visited by tourists, so feel free to order a delicious 'moqueca' (fish cooked in coconut milk and palm oil) in English.