Cut all the vegetables into rings. Sprinkle the eggplants with salt and leave them to drain out the bitterness.
Begin to arrange the vegetables in an oven dish with a grill bottom, alternating eggplant, zucchini, tomato. Once you've filled the tray, sprinkle it with plenty of soy sauce, spices and crushed vegetable broth.
Bake in the oven until they get a light tan.