Especially on Sunday noons, but as lovely on weekdays, the restaurant at Karera Beach is one of my favourites in town. The have good sangala (fish) and capitaine (another fish) and the view on the beach is just great.
Very good menu, local ingredients with a Belgian touch on the shores of the lake. Arguably the best restaurant in town. The building is very nice and it has even some history. It was on its grounds that, days before independence on 15 October 1961, the future head of state, prince Louis Rwagasore was assassinated.
The first "friterie" in town, le Petit Bruxelles is a nice place to have some Belgian fries or a small snack. They have draught beer and can be quite crowded in the evening, weekdays or weekends.