Dissolve yeast and sugar in 100 ml warm milk, cover and leave in a warm place to rise 10 minutes.
In another bowl, sift the flour and salt together. Make a well in the middle and add beaten eggs into it, the remaining warm milk, oil, vinegar and yeast mixture. Knead the dough with your hands or in your mixer until it separates from the sides of the bowl. Remove dough, place on lightly floured surface and knead for about 10 minutes until it becomes a soft, pliable dough .
Place in a greased bowl, cover with a towel and leave to rise in a warm place until doubled in volume - about an hour.Punch risen dough and transfer on a floured surface, divide dough into 2 equal parts.
Divide each of these again into 4, so you have 8 pieces of dough altogether .
Roll each piece of dough out into a roughly rectangular shape with a thickness of 3-5 mm .
Brush cooled, melted butter over each piece. Set aside remaining butter for later .
Place one piece of rectangular dough over another one and start to roll into a cylinder .
Do the same with the rest of the dough; you will end up with 4 cylindrical rolls altogether .
Cut each roll into three pieces in this way - slice at both ends of the roll about 1.5 inch long each, and put these two pieces aside .
Then cut the middle part of the roll into 4 triangles.
Preheat oven to 180C. Grease or line a large baking tray. In the middle of the tray, arrange the cut ends of the rolls around each other to form a circle, placing the cut sides down. Arrange the cut triangles to completely surround the middle circle. Cover with towel and leave the dough to rise in a warm place for about 30-40 minutes.
Beat the yolk with the milk with a fork to form a glaze and brush top of the bread with the glaze. (You can sprinkle with sesame seeds or other dry toppings at this point.) Bake bread for 20-30 minutes, reducing the temperature to 160C after 10 minutes in the oven .
Brush bread with melted butter as soon as it comes out of the oven, cover with a towel and leave to cool for 10-15 minutes before eating .