Sift the flour and salt and make a well in the middle. Beat the yoghurt with the egg and egg white. Pour in the egg mixture and effervescent yeast into the well. Knead a soft dough that doesn't stick to your hands. Set aside 392°F (200 °C) of it.
To the rest of the dough, add the crumbled feta cheese and savory to taste. Knead the dough again and roll it out into a medium thick sheet on a floured counter. Smear half of the sheet with oil, cut the other half into strips (but not all the way through).
Then, roll it up into a roll, starting from the non-cut side. Even out the edges and place thus formed roll along the edges of a cake form about 11 3/4″ (30 cm) in diameter that you've laid out with baking paper and smeared with oil.
Knead the set aside dough again and roll it out into a thin sheet, smear it with oil and wrap into a roll. Cut the prepared roll lengthwise into 2 parts and twist them together.
Then shape them a snail shell pattern and place in the middle of the form. Leave the pita to rise for about 1 hour. Smear with egg yolk and sprinkle with sesame seeds.
Bake in a preheated 356°F (180 °C) oven until ready.