In a large bowl, combine flour, salt, and sugar. Gradually add warm water, stirring until a dough forms. Knead for 8-10 minutes until smooth and elastic.

Cover the dough with a damp cloth. Let it rest for 30 minutes to relax the gluten.

While the dough rests, finely chop the scallions. Use only the green parts for a milder flavor. Set aside in a small bowl.

Divide the rested dough into 4 equal pieces. Roll each piece into a thin circle, about 8 inches in diameter. Aim for an even thickness of about 1/8 inch.

Brush a thin layer of sesame oil over the rolled dough. Sprinkle chopped scallions and a pinch of white pepper evenly across the surface. Leave a small border around the edges.

Roll the dough tightly into a log, like a jelly roll. Coil the log into a spiral, tucking the end underneath. Flatten the spiral gently with your hand.

Using a rolling pin, roll each spiral into a flat, 7-inch circle. Be gentle to keep the scallions from tearing through. The pancakes should be thin but sturdy.

Heat 1 tablespoon of vegetable oil in a non-stick skillet over medium heat. Place a pancake in the pan and cook for 2-3 minutes per side. Cook until golden brown and crispy.

Remove and drain on paper towels. Repeat with the remaining pancakes, adding more oil as needed.