The night before, process the sage leaves with the olive oil, leave at room temperature. Slice the eggplants into rounds 5 mm (¼ inch) thick. Drizzle the slices of eggplant with the sage oil.
The next day, barbecue the eggplant slices until soft, marking them with a criss-cross grill pattern. Season with sea salt, and garnish with a few sage leaves.