Aside from traditional botequins [1] and churrascarias, Flamengo and Botafogo have an increasing number of hip little cafés and some very fine bistros. Prices are generally lower than those in the fashionable Zona Sul, and you won’t find yourself rubbing elbows with tourists.
Links:
[1] http://www.moon.com/destinations/brazil/rio-de-janeiro/botequins