Place flour in a bowl. Add hot water in a slow, steady stream while mixing constantly. Add cold water; mix until no dry spots remain.
Transfer dough to a flat surface; knead lightly by hand until a ball is formed. Place dough in an oiled resealable plastic bag; seal the bag and let dough rest for 30 minutes.
Place scallions in a bowl; season with salt and pepper.
Turn dough out onto a floured work surface; roll into a thin rectangle using a rolling pin. Spread butter over dough to cover; sprinkle evenly with salt and pepper. Spread scallions over dough, leaving top edge empty. Roll dough up from the opposite edge, keeping scallions in place and pulling dough a little with every roll to make it tight.
Cut roll into 3- to 4-inch-long pieces; pinch and seal ends of each piece. Lightly flatten each piece into a circular pancake.
Heat oil in a nonstick skillet; cook pancakes until golden brown, about 3 minutes per side. Crush 2 sides of the pancakes with spoons or ladles until flaky.
