How to Make It
In a small bowl, mix the minced scallions with 1 tablespoon of the sesame oil and the salt. Cut the dough in half. On a work surface, roll out each piece of dough to a 10-by-6-inch rectangle. Spread the scallion mixture over the dough, leaving a 1/2-inch border all around. Starting at a long edge, roll up each piece of dough and pinch to seal. Coil each roll of dough into a round and tuck the end under the coil. Cover and let stand for 15 minutes.
Meanwhile, in a bowl, mix the sliced scallion with the remaining 1 teaspoon of sesame oil and the soy sauce, water and vinegar.
With a large, heavy rolling pin, roll out each dough coil into an 8-inch round. (It's okay if some of the scallion mixture comes out; it will stick to the dough as you roll.)
In a large skillet, heat the canola oil until shimmering. Fry one pancake at a time over moderately high heat, turning once, until golden, about 3 minutes total. Drain on paper towels. Cut the pancakes into quarters and serve with the soy dipping sauce.