Prepare the aubergine and courgettes ahead of time by cutting them into 1 inch (2.5 cm) dice, leaving the skins on. Then toss the dice in about a level dessertspoon of salt and pack them into a colander with a plate on top and a heavy weight on top of the plate. Leave them on one side for an hour so that some of the bitter juices drain out.
After that, squeeze out any juices left, and dry the dice thoroughly in a clean cloth. Now arrange the tomatoes, aubergine, courgettes, peppers and onion in the roasting tin, sprinkle with the chopped garlic, basil and olive oil, toss everything around in the oil to get a good coating, and season with salt and pepper. Now place the tin on the highest shelf of the oven for 30-40 minutes or until the vegetables are toasted brown at the edges.