Peel and wash the potatoes and cook them in boiling salted water for about 15 minutes. In the meantime, clean, wash and chop the beans. Cook in boiling salted water for about 10 minutes.
Wash, clean and slice the tomatoes. Peel onion, cut into rings and fry in hot oil. Cut the feta cheese into cubes. Drain the potatoes and let them cool down a little. Drain beans as well and rinse with cold water.
Wash parsley, dab dry, chop and stir into the crème fraîche. Cut the potatoes into slices. Layer potatoes, tomatoes, beans and onions in a flat casserole dish. Season with salt and pepper.
Pour crème fraiche as a blob over the casserole. Sprinkle the sheep's cheese over it and bake in a preheated oven (electric range: 200 °C/ gas: level 3) for approx. 20 minutes until golden brown.