Melt yeast with warm water and then stir water with all purpose flour. Use a chopstick or rubber to help. The dough might be a little bit soft and sticky, you can slightly fold them up with fingers. Then cover the rest for 30 minutes at least until the dough becomes double in size.
Heat oil in wok and then pure the oil in flour. Mix well. This helps to creates layers.
Then brush some oil on surface to avoid sticky and the spread the dough. (roughly re-knead the dough) with salt and Chinese five spice powder. Then slightly roll out to a larger piece. Add the oily flour, sprinkle chopped green onion or scallion.
Roll up the circle into a cylinder. Close the two ends and slightly stretch the log, further roll into the shape of a snail.
Roll out to a large round pancake. Press sesame seeds on top.
Prepare a cast iron pan and a cover. Transfer the pancake to the pan and then slightly press with hands to adjust the shape. Cover and set aside for another 10 to 15 minutes. (second proofing)
Heat with slow fire and fry one side for 4 to 5 minutes until the pancake becomes hardened and crispy. Then over the fry the other side too. It is extremely important to use slow fire and cover the lid in order to make sure the inside layers are well cooked.