In a small saucepan, bring 1/2 cup water to a boil. In a medium bowl, combine the flour with 1/2 teaspoon salt. Slowly stir in the boiling water with a fork until a sticky ball forms. Wrap the dough in oiled plastic wrap and let rest for 45 minutes, or overnight in the refrigerator.
On a floured surface, using a floured rolling pin, roll out the dough into a thin rectangle, about 8 by 10 inches. Brush with the sesame oil, sprinkle with the scallions and season with salt and pepper.
Roll up the dough from the long side, jelly-roll style, and cut crosswise into 4 equal pieces. Roll out 1 piece into a thin rectangular pancake with the floured rolling pin; fold in half and flatten again into a pancake; repeat the folding and flattening a few more times, dusting with a little extra flour if necessary to prevent sticking. Repeat with the remaining pieces of dough to form four rectangular 1/8-inch-thick pancakes, scraping the sticky dough from the rolling pin and work surface, and adding a light sprinkle of flour between each turn.
In a large skillet, heat 1 to 2 tablespoons oil over medium heat. Fry the pancakes 2 at a time until the edges are golden brown, about 4 minutes per side. Remove, cut into wedges and sprinkle with salt.