Sift the flour with the salt. In a bowl, dissolve the yeast in the warm water along with the sugar. Beat the eggs with the oil, vinegar and yoghurt. Add them to the flour, then add the yeast. Knead a stretchy dough. Leave it for 10 min. to relax.
Divide the dough into 2 parts. Roll out both of them into thin sheets. Smear one with oil and cover with the 2nd rolled out sheet. Sprinkle again with oil and crumbled feta cheese. Roll it up, twist and stretch to obtain a long wick. Oil a tray and wrap the wick in a spiral shape in it.
Place pieces of butter on top and bake at 392°F (200 °C) for about 35-40 min. Take it out of the oven and leave to cool, covered with a clean towel. Make New Year's fortunes and stick them in the phyllo pastry on top.