Saute finely chopped onion with sliced garlic in a tablespoon of oil and season. Mix with tomato sauce and lavender flowers and set aside for infusion.
Zucchini, zucchini and eggplant should have the same diameter to cook evenly. They are sliced to the same thickness, and the pepper is cut into thin stalks.
In a heat-resistant tray, place the mixture of tomato and lavender sauce evenly, and over the sliced vegetables: first a slice of zucchini, then one of eggplant and one of zucchini and repeat the placement forming a circular fan starting from the outside to the inside . Place the peppers on top and sprinkle with the remaining oil, Provencal herbs, salt and pepper.
Cut a baking paper lid suitable for the tray used and place it on top of the vegetables.
Place the tray in the preheated oven at 190 degrees where it will remain for 50-55 minutes until the water has been absorbed.
To place on a plate, take a fairly long sequence of vegetables and place them in a vertical circle. Place a lid on top of a slice of each vegetable and serve with the sauce left in the pan.