Dissolve the yeast in luke-warm milk, with a pinch of sugar and allow to rise for about 15 min.
Place the following ingredients into a bowl: flour, sugar, vanilla sugar, butter (cut into small pieces), egg, egg yolk, lemon zest, cream and salt. Now add the leavened yeast mixture into the bowl and stir constantly, for at least 10 min to create a smooth dough. Lightly dust the dough mix with flour, then cover with a tea towel and leave in a warm ambience for about 30 min until its volume has increased twofold.
Divide the dough into 6 equal parts, and create long strips, braided into 2 plaits. Place them on a baking tray lined with parchment paper for baking, covered with a tea towel, and leave to rise for about 30 min. Then brush the entire surface of the plaits with raw egg yolk, and then sprinkle with hail sugar. Place into a preheated oven for approx. 20 min to bake at 180°C, until golden brown.