Clean and wash the tomatoes, eggplant and round zucchini. Cut off the top of each and hollow them out with a small spoon. If necessary, cut straight at the bottom so that you stand better. Salt the inside and place the vegetables on kitchen paper with the opening facing down
Clean and wash the remaining zucchini and fennel. Cut into very small cubes with the flesh removed. Peel and dice the onions. Heat 2 tablespoons of oil in a frying pan. Fry the onions in it until transparent. Add the diced vegetables and cook for about 10 minutes, stirring occasionally. Season with salt and pepper. Wash basil, shake dry. Pluck the leaves from the stalks and chop them, except for a little bit for garnishing
Fill the zucchini, tomatoes and aubergines with the vegetable mixture. Place in an ovenproof dish, drizzle with 4 tablespoons of olive oil and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 30-40 minutes. Remove the vegetables, let them cool down a little, garnish with basil and serve