Sift the flour and 3/4 teaspoon salt into a large bowl. Stir in 1/2 cup hot water until blended. If the dough is dry, add up to 2 more tablespoons water. Knead on a lightly floured surface until elastic yet firm, about 5 minutes. Cover with a damp cloth and set aside for 30 minutes.
Divide the dough into 6 pieces and keep covered. One at a time, roll each piece into a 4-inch-long log, then stretch into a 14-inch-long rope. Brush with shortening and sprinkle with about 1 tablespoon scallion. Coil the dough into a circle, cover and set aside. Repeat with the remaining dough. Flatten the coils with your hand on a floured surface, then roll with a floured rolling pin into a thin circle. Cover and refrigerate for at least 2 hours.
Heat 1 tablespoon oil in a 10-inch nonstick skillet over medium-high heat. Add 1 pancake and cook until golden brown, about 2 minutes per side. Drain on paper towels and repeat with the remaining pancakes, adding more oil as needed. Cut into wedges to serve.
For a dipping sauce, mix 1 tablespoon each sesame oil and sugar, 2 tablespoons each water and soy sauce and sliced scallions.