Wash the potatoes and cook in boiling water for about 15 minutes. In the meantime peel onions and garlic. Dice garlic finely. Heat 1 teaspoon of oil in a pan and fry the garlic.
Deglaze with tomatoes, stir in herbs and let it boil down for about 15 minutes. Wash, clean and slice the zucchini and eggplant. Quarter the peppers, clean, wash and cut into pieces.
Cut onions into slices. Heat 2 tablespoons of oil in a coated pan, fry the vegetables in it. Season with salt and paprika. Drain potatoes, rinse and peel. Season tomato sauce with 1 pinch of sugar, salt and pepper.
Cut the potatoes into slices. Place the potato slices, vegetables and tomato sauce in an ovenproof casserole dish. Drain the feta cheese and crumble into pieces. Sprinkle cheese over the casserole. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 25 minutes.
Remove and serve garnished with oregano.