Žjelo (also spelled Žejo) is consistently rated the best ćevapi restaurant in Sarajevo, which in a city this devoted to the dish is a meaningful claim. It operates from a tiny, perpetually crowded space in Baščaršija, with queue times that can reach 30 minutes on busy weekends. The ćevapi here are small, dense, and heavily spiced, served in a portion of ten with somun flatbread, raw onion, and kajmak (a clotted cream dairy product similar to high-fat crème fraîche).
The menu is short because the focus is absolute: ćevapi are what they do, and everything else is peripheral. Order the standard portion, add extra kajmak, eat it while standing at a high table in the side room. It is cheap enough that getting seconds is a realistic option. Go outside peak mealtimes if you dislike queuing.