Stir the flours and salt in a mixing bowl with a wooden spoon. Add the corn oil and the boiling water, and stir until a rough dough forms. If the dough is too soft, knead in about ¼ cup more flour. Turn the dough out onto a lightly floured surface and knead for 5 minutes, or until smooth, kneading in more all-purpose flour as necessary. Cover with a cloth or wrap in plastic wrap and let rest for 30 minutes, or longer if possible.
On a very lightly floured work surface, roll the dough into a long snakelike roll about 1 inch in diameter. Cut the roll into 24 pieces. Keep the unused dough covered with a damp towel as you work.
With a rolling pin, roll out one piece of dough, cut side down on the work surface, into a 5-inch circle. Brush the top with a little sesame oil and sprinkle with some of the minced scallion greens. Roll up the circle like a jelly roll and pinch the ends to seal. Flatten the roll slightly with the rolling pin, and coil it into a snail shape, with the seam on the inside. Pinch the end to secure it and set aside on a lightly floured surface. Prepare the remaining pancakes, and let them rest for 30 minutes uncovered.
Reflour the work surface and roll each coiled pancake out to a 4-inch circle. Place them on a lightly floured tray. Let them rest for 30 minutes uncovered, or longer if possible. Preheat the oven to 200°F.
Heat a large, heavy skillet, add the oil, and heat to 350°F. Put a few of the pancakes in the pan, not touching, and fry over medium heat, turning once, until golden brown and crisp on both sides, about 2 to 3 minutes. Remove with a spatula and drain briefly in a colander, then transfer to absorbent paper. Arrange the cooked pancakes on a cookie sheet and keep them warm in the oven while you fry the remaining pancakes, reheating the oil between batches. Serve immediately or keep them warm in the oven.