Put the eggplant in layers in a colander, sprinkling salt on each layer. Leave the eggplant for 1 hour to degorge, then rinse and dry. (The eggplant is left to degorge for 1 hour, so that less oil is needed for frying.)
Heat half the oil in a large flameproof casserole dish over medium-high heat. Fry the eggplant in batches for 5–6 minutes, unt