Wash the tomato and zucchini and dab dry. Cut the tomato into slices. Cut the zucchini lengthwise into thin slices with a wide peeler. Leave half of the zucchini and use it for other purposes. Cover the slice of bread generously with slices of zucchini and tomato.
Season with pepper and a little salt. Crumble the feta cheese and put it in a bowl with sour cream. Stir with the whisk of the hand mixer until smooth. Place bread in an ovenproof flat dish and spread the icing on top. Sprinkle with herbs and bake under the preheated grill for 5-6 minutes