Step 1: In a large mixing bowl, combine the all-purpose flour and ½ teaspoon of salt. Gradually pour in the hot water, stirring with chopsticks or a wooden spoon until a shaggy dough forms.
Step 2: Turn the dough out onto a lightly floured surface. Knead for 5-7 minutes until the dough is smooth and elastic. It should feel soft and slightly tacky, but not sticky.
Step 3: Cover the dough with a damp cloth or plastic wrap and let it rest at room temperature for at least 30 minutes. This makes the dough easier to roll.
Step 4: Divide the rested dough into 4 equal portions. Take one portion and, on a lightly floured surface, roll it into a very thin rectangle, about 8x10 inches.
Step 5: Brush the entire surface of the rolled dough with about 1 tablespoon of sesame oil, leaving a small border. Sprinkle generously with ¼ cup of finely chopped green onions and a pinch of the remaining salt and black pepper.
Step 6: Starting from one long edge, tightly roll the dough into a log. Then, coil the log into a spiral shape, like a snail shell. Tuck the end of the log underneath the coil.
Step 7: Gently flatten the coiled dough with your palm. Carefully roll this flattened coil into a disk, about 6-8 inches in diameter and ¼-inch thick. Repeat steps 4-7 for the remaining dough portions.
Step 8: Heat a large non-stick skillet or cast-iron pan over medium heat. Add 1-2 tablespoons of vegetable oil.
Step 9: Carefully place one pancake into the hot oil. Cook for 3-5 minutes per side, or until golden brown, crispy, and cooked through. Adjust heat as needed to prevent burning.
Step 10: Transfer the cooked pancake to a cutting board, slice into wedges, and serve immediately with your favorite dipping sauce. Repeat with the remaining pancakes, adding more oil to the pan as necessary.