Dissolve the yeast, salt and sugar in lukewarm water. Sift about 700 g of flour and doing well. The rest of the flour to knead use. In the well send down liquid yeast mixture, add the yogurt and egg. Knead the dough smooth and elastic. Transfer the dough in a greased baking pan and leave to rise, covered with a cloth. Bake in a preheated 180C degrees oven about 35 minutes.