For the ratatouille, heat the oil in a pan and fry the aubergine and zucchin slices in it until tender. Add the garlic and thyme and fry for 1 minute. Then the vegetables with salt and pepper
Season to taste and let cool.
Cut the mozzarella balls into 4 equally sized slices, then lightly salt and pepper.
Distribute the ratatouille evenly over four of the mozzarella slices. Place the remaining cheese slices on top so that you have a total of four filled mozzarella sandwiches. Now wrap each sandwich with two slices of ham to prevent the filling from leaking later. Cover and let cool for at least 30 minutes.
Heat the butter in a large frying pan and fry the mozzarella sandwiches until golden yellow on each side for about 2-3 minutes. Arrange the finished sandwiches on four serving plates.
Mix the ingredients for the dressing vigorously and season with salt and pepper. Pour the sauce over the mozzarella sandwiches and serve immediately.