Mix the yeast in the lukewarm milk with the teaspoon of sugar and let it rest for 5 minutes. Put the flour, yogurt, and yolk in a bowl and mix vigorously to remove the lumps. Stir in the milk. Whip the egg white with a pinch of salt and fold it into the batter. Let it rest and rise for an hour.
Grease your pancake pan a bit, briefly and gently stir your batter and place spoonfuls of batter in the warm greased pan, let it cook, when holes appear on the surface you can flip them. Let them cook a bit longer and place on a rack, keep warm. Cook the rest of the batter in the same way. Top with your favorite toppings and serve immediately.