Mix all-purpose flour with salt.

Pour warm water and mix well with chopsticks.

Knead the dough until smooth.

Roll it into a long log and divide the dough into 8 portions using a dough cutter.

Roll each dough portion into a small ball, then shape into cylinders.

Transfer to an airtight container and cover with a lid or plastic wrap to seal. Covering it is important to prevent the dough from drying out and absorbing too much air.

Let it sit for half an hour.

Soak the meigan cai in water for 20 minutes. Set aside.

Prepare the meat or plant filling. Blend the pork belly with some chopped green onions.

Season with salt, light soy sauce, and white pepper. Mix it well.

Drain the soaked meigan cai and squeeze out as much water as you can. Mix it with the filling, along with chopped green onions, a bit of edible oil, and a pinch of white sugar. Stir well.

Make the oil paste by combining flour, salt and pepper seasoning, and edible oil. Keep mixing until you have a smooth, creamy but runny paste.

Take out the dough portions and roll out each into a thin oblong strip. Use a rolling pin for this step.

Brush the oil paste on top using a pastry brush.

Then, roll it up from one end to the other, making it look like spring rolls.

Seal both ends by pinching the edges together and sealing the rolled up end.

Press the dough with the palm of your hand, giving you a flattened ball of dough.

Use a rolling pin to flatten the dough into a thin, circular wrapper, making sure the center is slightly thicker than the edges. This step is similar to making the bun wrapper for egg yolk buns. To do this, use one hand to hold and spin the dough and the other hand to roll the rolling pin to flatten the edges. Repeat these steps for the rest of the dough portions.

Place a portion of the filling (about 2 tablespoons) on the center of each dough wrapper and seal the edges to form a creased bun.

Roll the buns as thin as possible until you have a thin oblong flatbread dough. To do this step, roll the rolling pin until it flattens, then turn the dough to the other side and roll it out again. Keep rolling and turning the dough until it is larger in size and thinner. Don't worry if it tears a bit; it's okay. In this step, it helps to lightly dust the surface with a bit of flour to prevent the thin dough from sticking to the surface.

Lightly spray it with water and sprinkle sesame seeds on top.

Place each flatbread on a sheet of parchment paper. I recommend placing the dough on parchment paper to prevent it from sticking to the surface.

Transfer the flatbread with the parchment paper to a baking tray.

Bake the guo kui in a preheated oven at 230 degrees Celsius for 9 minutes or until golden brown and crispy.

Alternatively, pan-fry them with a spray of oil until crispy and golden brown on both sides.