Sprinkle the yeast over the surface of the warm milk and set aside to proof.
Place the flours, sugar, baking powder, and salt in a large mixing bowl and stir to combine.
Make a well in the center, and add the milk/yeast, yogurt, and oil.
Knead the dough (either by hand or on low speed, using the dough hook attachment), until soft and pliable. (If the dough seems too dry, add a little warm water to bring it together. It should come away from the sides of the bowl, and be soft but not sticky.)
Cover the dough with plastic wrap, and set in a warm place to rise for 2 hours or until doubled in size.
Preheat a cast iron griddle on medium-high heat. Punch down the dough and divide into balls about the size of a lime.
Roll each ball with a rolling pin, to a thickness of about ¼ inch.
Sprinkle the surface of the dough with water, and place on the hot pan.
When the bottom is brown and there are lots of big bubbles on the surface, flip it and cook it on the other side. If desired, brown the surface over an open flame.