Halve dough; using a rolling pin, roll 1 dough half into a 10″ x 20″ rectangle. Brush with 1 tbsp. canola oil and half the sesame oil. Sprinkle with half the scallions, half the chile flakes, and half the white pepper. Beginning with one long side, tightly roll dough like a jelly roll. Cut roll crosswise into 3 pieces, slightly stretch each piece, and starting from one edge, coil piece horizontally, tucking the end underneath. Using your hand, gently flatten coil into a disk; using a rolling pin, flatten into a 5″ circle.