Dilute the yeast in cool water. In a tray, pour the flour and make a well. Pour the beaten yeast in it. Add the salt, sugar, yoghurt and oil.
Break 2 whole eggs in, plus only the egg whites of 2 more. We're going to be using yolks later to smear the pita with. Knead a soft dough.
Wrap it with a towel and leave in a warm area to rise. Then knead it again. Depending on the amount of resulting dough, divide it into 2-3 balls.
Roll out each ball and smear it with melted butter. Wrap each into a roll. Cut off a little bit from each end. Cut the rest of the roll into pieces about 3 fingers thick.
Arrange the pieces in an oiled tray, about 1/8" apart from one another. Cover the tray with a towel and leave the pita to rest in a warm area for 30 min.
Then smear with a mixture of the beaten egg yolks, oil and vinegar. Sprinkle with sesame seeds. Bake in a preheated 392°F (200 °C) oven about 40 min.