Peel aubergines and slice thinly. Sprinkle with salt and place slices under a weight for ½ hour. Rinse thoroughly with cold water, drain and dry. Slice tomatoes and onions thinly. Keep separate.
Arrange a thin layer of onion slices in the bottom of a shallow baking dish, then a layer of aubergine slices, then one of tomato slices. Season with freshly ground black pepper. Repeat until al