Wash the zucchini and tomatoes. Cut the zucchini into round slices with a thickness of half a finger. In a suitable greased rectangular tray, place the tomatoes in the middle. Around them, start to stack the zucchini in rows, overlapping them as you go.
Sprinkle some crumbled feta cheese between the rows, if necessary add salt and pepper. Beat the eggs well and add them to the cream (milk, or water), flour and spices to taste and beat well. Finally, mix with vinegar.
Put the zucchini with tomatoes in the tray and gently shake to distribute the topping. Put the dish to bake in a moderately heated oven at 392°F (200 °C) for 20-30 minutes or until the topping firms up and the vegetables are toasted.