Wash the savoy cabbage leaves and cut out the stalk. Blanch leaves in boiling water for 3-5 minutes. Drain. Peel onion and chop finely. Heat the oil in a pan and sauté the onion.
Deglaze with 1/4 litre stock and bring to the boil. Add the lentils and cook over low heat for about 8 minutes. Drain if necessary. Finely chop the feta cheese. Clean and wash spring onions and cut into rings except for 8 long ends.
Put the ends of the spring onions briefly in hot water and let them drain. Mix lentils, sheep's cheese, except for something to sprinkle, and leek and onion rings and season with salt and pepper. Place 1 tablespoon of lentil and sheep's cheese mixture in the middle of each savoy cabbage leaf.
Whip the savoy cabbage edges over the filling and roll up. Tie together with the ends of the spring onions. Bring the rest of the stock to the boil. Place the savoy cabbage roulades inside and cook over a low heat with the lid on for 20-25 minutes.
Remove the savoy cabbage rolls and keep warm. Add wine and yoghurt to the stock and stir in. Bring to the boil briefly and thicken with sauce thickener. Season with salt and pepper. Arrange roulades and sauce on a plate and serve sprinkled with the remaining feta cheese.
Flatbread tastes good with it.