Under most circumstances, Manca Studio’s renovation of the restaurant Oi Marì in Matera, a small city on a rocky outcrop in southern Italy, might be called minimalist. It features a concise material palette of rusty weathering steel, frameless glass and unfussy oak furniture; in the architects’ words, the project proceeded with the guiding aim of “subtraction, not addition.” But such a characterization underplays the warmth and wit of the intervention, and more importantly ignores the impact of its setting, in a labyrinthine limestone cave.