Make the dough: Combine all the ingredients in a large mixing bowl. Mix with a stiff spatula until no dry bits of flour remain. Cover with plastic wrap and set aside for 15 minutes. 
240 grams all-purpose flour, 60 grams whole wheat flour, 113  grams sourdough discard, 56 grams yogurt, 8 grams salt, 10 grams baking powder, 113 grams water
Knead:  Turn the dough out on a lightly oiled surface and knead until completely smooth, soft and supple.
Shape the dough: Divide the dough into 8 portions. Round each into a tight ball, cover with plastic wrap and let the dough rest until ready to use. Working with one portion of dough at a time, use a floured rolling pin to flatten it out into a 6-inch disc. Place 4 portions on each lined baking sheet.Letting your dough rest for 5 to 10 minutes will make it easier to roll out.  Prep: Preheat your oven to 500 F with a rack in the center of the oven. Line two large baking sheets (18 by 13 inches) with parchment paper. 
Bake: Bake only one baking sheet at a time. Bake the dough for 3 to 5 minutes on each side, flipping in between. If you’d like your flatbread to be a little more browned, broil them for 1 minute on each side. 
Steam the flatbread: Place the baked flatbread on a bowl lined with a clean tea towel, wrap the towel around the flatbreads. Bake the remaining dough and steam the flatbread for at least 5 minutes. This softens the crust slightly resulting in soft, tender, tearable flatbread.  Store: Store any leftovers in a ziptop bag for up to 3 days at room temperature, refrigeration will dry out your flatbread.
Reheat: Preheat a dry frying pan. Reheat the flatbread for 5 to 10 minutes, flipping in between. Wrap the hot flatbread in a piece of aluminum foil and let it steam for 5 minutes. Enjoy!