Wash all the vegetables. Cut the aubergines into cubes; put them in a colander, sprinkle with salt and leave so that their water drains off for at least half an hour. Remove the ends of the courgettes, then cut them into rounds ½ cm thick. Brown on both sides in a non-stick pan with 2 tablespoons of olive oil and then transfer them onto a large plate. Clean the peppers, removing the seeds and white, internal rib; cut them into rings and sauté them with 2 tablespoons of olive oil. Do the same with the potatoes (washed, peeled and cut into round slices) and the rinsed and dried cubes of aubergine. Put all the sautéed vegetables on a large plate.
Peel and chop the tomatoes. Clean and slice the onion and sauté it in a pan with 2 tablespoons of olive oil, the garlic and chilli pepper. After 2 minutes, add the tomatoes and cook another 5-6 minutes. Add all the other vegetables that you have cooked previously and continue to cook, over a moderate heat, for a further 10-15 minutes, stirring delicately. Season with salt to taste and add the basil.
This colourful mixture of vegetables is excellent as a side dish, but it can also be used as a sauce for pasta (in particular short shapes), accompanied with grated Parmigiano and a pinch of powdered chilli pepper. It can also be used to fill a "calzone" (using bread dough) with the addition of pieces of mozzarella.
NB: cooking all the vegetables individually makes the preparation of this recipe a bit longer, but it helps you have vegetables that are well cooked, not overcooked, and look and taste better.