We had been meaning to go to the "Little Yellow House that is a Restaurant on the Lagoa" for quite some time, and finally made it there while my mom & sister were here. It was fantastic! We will definitely be back. It is actually called Pomodorino. The service was incredible, the food and ambiance fantastic and it is VERY REASONABLE! (With today's exchange rate especially). I recommend it!
Avenida Epitácio Pessoa, 1104 - Lagoa
(entre as Ruas Garcia D´ávila e Maria Quitéria)