To make dumpling dough, sieve the flour to a bowl, add water, egg and a pinch of salt. Throw a dough until a ball of dough is formed and it doesn`t stick to your hands. Add some more flour, if needed. Leave the dough for 30 minutes.
Meanwhile prepare filling for the dumplings. To do this, chop the onion, mushrooms, spinach and Black Garlic cloves. First, fry the onion in coconut oil or butter for a couple of minutes, then add mushrooms and lastly, the spinach and fry the mixture stirring constantly for a few more minutes. Season with salt and pepper. Leave the mixture to cool for a minute and add pieces of Black Garlic.
Roll the dough thin and press circles from it with a glass of suitable size. Place a tablespoonful of vegetable mixture and feta cheese bits onto the edge of every circle, lift the other edge of the circle on top of the mixture and press the edges together with a fork. Place dumplings on a pan and brush them with egg yolk. Bake the dumplings at 180 °C in the oven for 15 minutes or until they are golden brown. Serve them with sour cream and herbs.