Warm the milk (lukewarm not boiling), stir in the yeast, and let sit until yeast is activated - about 10 minutes.
In a separate bowl, mix together the flour and the salt.
Once the yeast is activated, add to the flour along with the yogurt and water.
Turn mixture onto a floured surface and knead. The dough should be sticky so avoid adding additional flour. Return the dough to the bowl, cover and allow to rise in a warm place until doubled in size - about 1 1/2 hours.
Preheat the oven and the baking tray to your oven's maximum temperature. For me this is 450 degrees.
Return proofed dough to a floured surface and divide into 4 equal parts.
Shape each portion into a ball, turn it in the flour adn using your fingers to form a flat shape. Do not use a rolling pin as this will remove the air from the dough. The somun should be about the thickness of a finger.
Place the somun on parchment paper and allow to rise while the oven is preheating.
With the back of a knife or a wooden skewer, create a grid on top of each somun.
Put the somuns in the oven - do this as fast as possible to prevent the oven from cooling down. Bake for 7-10 minutes. Length will vary depending on the heat of the oven. They are done when inflated and golden brown.
Remove from the oven and wrap in a kitchen towel to keep warm until needed.