Step 1 (Make Dough: In bowl, mix 2 cups flour with 1/2 tsp salt. Slowly add 3/4 cup hot water while stirring with chopsticks until shaggy dough forms. Add 1/4 cup cold water, mix until combined. Knead on floured surface for 8-10 minutes until smooth and elastic. Cover with damp cloth, rest at room temperature for 30 minutes (gluten relaxation critical for rolling).
Step 2 (Prepare Filling: Finely chop scallion greens (use green parts only for better color and flavor). Mix with 1 tsp salt and 2 tbsp toasted sesame oil.
Step 3 (Roll and Layer: Divide dough into 6 equal balls. Roll one ball into thin rectangle (10×8 inches). Brush surface lightly with vegetable oil. Spread 1.5 tbsp scallion mixture evenly over surface.
Step 4 (Create Layers: Starting from long edge, roll dough tightly into log. Pinch ends to seal. Coil log into spiral like snail shell, tuck end underneath. Flatten gently with palm. Repeat for all balls. Cover and rest 10 minutes.
Step 5 (Final Roll: On floured surface, roll each spiral into 6-inch circle, 1/4-inch thick (do not roll too thin or layers will merge).
Step 6 (Pan-fry: Heat heavy skillet over medium heat. Add 2 tbsp oil. When oil shimmers (180°C/350°F), add pancake. Cook 3-4 minutes per side, pressing gently with spatula, until golden brown and crispy. Flip only once.
Step 7 (Serve & Store: Remove to cutting board, let rest 1 minute, then cut into wedges. Serve immediately with dipping sauce. Best consumed same day. Reheat in dry skillet over medium heat for 2 minutes per side to restore crispness. Freeze uncooked rolled pancakes between parchment for 3 months; cook from frozen, adding 2 extra minutes per side.