Cook the flour and water on stovetop to make the tangzhong. Once it is thick, remove from the flame and set aside.
Add all the ingredients listed under "For the Dough" int the bread machine and set it on dough cycle. Let it prove for an hour.
In the mean time, add all the filling ingredients except oil to a bowl. Heat sesame oil and add it to the scallion mixture and mix well. Divide the filling into three equal portions.
Once the dough has doubled, punch and knead the dough. Divide it into four equal portions.
Roll a portion of the dough into a 10-11 inch circle. Spread a portion of the filling. Then place another dough circle and filling, repeating until the filling is complete. Finally place a dough circle and seal the edges.
Preheat the oven to 375℉.
Place a 2-in cup in the center. Use that as a guide for the center. Start from the edge of the bowl and cut it into 16 strips. Gather two adjacent strips. Twist each strip in opposite directions, join the edges together to seal. Repeat with the other strips creating a star shape.
Sprinkle with sesame seeds and flaky salt.
Bake in the oven for 23-26 minutes. the bread should sound hollow when tapped from the bottom. Remove from the oven and cool.
Serve warm as such or with a soy dipping sauce.