Meanwhile, preheat oven to 180 °C top and bottom heat.
Wash the zucchini and tomatoes, remove the base and stalk, cut into 3 cm cubes and place in the casserole dish. Peel the potatoes, cut into 1 cm cubes and add to the casserole dish. Cut the feta into cubes of about 1 cm, add to the casserole dish and mix altogether.