In a large mixing bowl, combine together the flour and cold water while stirring with chopsticks. When the dough starts becoming flaky, knead the dough until it becomes smooth (add more water or flour if necessary). Divide into two balls and cover with a damp cloth. Let it rest for 20 minutes.
On a lightly floured surface, roll out the dough into a thickness of 0.1 cm.
Sprinkle on half of the salt, and roll the salt around the dough. Then, spread on half of the oil, ensuring every part of the dough is spread with oil. Top off with half of the chopped scallions.
Roll the dough tightly into a log and seal both ends. Then, twist the dough. Roll the dough inwards from the bottom to the middle, and repeat the same process for the other half of the log, forming a spiral. Repeat steps 3 and 4 for the other half of the dough. Cover and let it rest for 20 minutes.
On a lightly floured surface, roll out the dough into a thickness of 0.5 cm.