Prepare the Dough: In a large mixing bowl, combine the flour, yeast, sugar, and sea salt. Slowly add the tepid water and mix until a dough forms. Knead the dough for 5-7 minutes until smooth and elastic. Cover with a damp cloth and let it rest for 1 hour, or until the dough doubles in size.

Season the Dough: Once the dough has risen, punch it down and roll it out into a large rectangle (about 1/4-inch thick). Brush the surface with oil, then sprinkle evenly with white pepper, ground Sichuan peppercorns (if using), and chopped scallions.

Form the Flatbread: Starting from one edge, roll the dough into a tight cylinder. Coil the cylinder into a spiral, then gently flatten the spiral with your hands or a rolling pin until it’s about 1/2 inch thick. Brush both sides of the flatbread with oil and sprinkle with sesame seeds.

Cook the Flatbread: Heat a skillet over medium heat and add a small amount of oil. Place the flatbread in the skillet and cook for 3-4 minutes on each side, or until golden brown and crispy. The flatbread should be soft on the inside with a crispy, golden exterior.

Serve and Enjoy: Slice the flatbread into wedges and serve immediately. This Shanghai Scallion Flatbread is best enjoyed warm, fresh out of the skillet, as a snack or appetizer alongside a dipping sauce of your choice.