For the Bärlauchtascherl boil the potato and grate coarsely. Wash the wild garlic thoroughly, spin dry and chop coarsely. Fry the onion in a little oil. Then add the wild garlic and let it fall together. Cook for about 5 minutes.
Mix potato with wild garlic, sour cream, diced feta and season with salt and pepper. Cut the puff pastry into 6 rectangles. Put some of the filling in the center of each rectangle and fold them together.
Press the edges with a fork. Place the 6 pieces on the baking tray, brush with beaten egg and bake at 175 °C for about 20 minutes. Serve with herb sauce and potato.