Place flour and salt in bowl of food processor. With processor running, slowly drizzle in about 3/4 of boiling water. Process for 15 seconds. If dough does not come together, drizzle in a little more water and process again, until it just comes together. Do not over work the dough, it will make it tough. Transfer to a floured work surface and knead a few times to form a smooth ball. Transfer to a bowl, cover with a damp towel or plastic wrap, and allow to rest for 30 minutes at room temperature, or up to overnight in the fridge.
Remove dough from bowl and divide into four even pieces. On a lightly floured surface, roll out one ball at a time into a circle about 8-inches in diameter. Using a pastry brush, paint a very thin layer of sesame oil over the top of the disk. Roll disk up like a jelly roll.
Twist the roll into a tight coil like a snake, tucking the end underneath. Flatten gently with your hand, then re-roll into an 8-inch disk.
Brush re-rolled dough with another layer or sesame oil, sprinkle with 1/2 cup scallions, and roll up like a jelly roll again. Twist into a spiral, flatten gently.
Re-roll into a 7-inch disk. Repeat steps two and three with remaining pancakes.
Combine all the sauce ingredients and set aside at room temperature.
Heat oil in an 8-inch nonstick or cast-iron skillet over medium-high heat until shimmering and carefully slip pancake into the hot oil. Cook, shaking the pan gently until first side is an even golden brown, about 2 minutes. Carefully flip with a spatula or tongs, and continue to cook, shaking pan gently, until second side is even golden brown, about 2 minutes longer.
Transfer to a paper towel-lined plate to drain. Season with coarse salt, cut into 6 wedges. Serve immediately with sauce for dipping. Repeat with remaining 3 pancakes.