Combine 4 cups of flour and ½ teaspoon of salt in a large mixing bowl. Make a well in the center, and add in the boiling water. Mix until partially blended. Then add in 2/3 cup of room-temperature water. The dough will be soft and slightly sticky.
Remove the dough from the bowl, and place it on a floured surface. Knead for 2 to 3 minutes until smooth.
Brush the ball of dough with some oil, and transfer it into a bowl that's covered with plastic wrap. Let it sit for 30 minutes. Wrap the dough in the plastic wrap, and refrigerate it overnight.
The next day, if your Sichuan peppercorns are whole, grind 1 ½ teaspoons in a spice grinder.
Add 1 cup of thinly sliced scallions, ½ cup of flour, 1 ½ teaspoons of ground peppercorns, and 1 teaspoon of salt to a mixing bowl. Heat ½ cup of avocado oil in a saucepan on medium heat. When the oil is hot, pour it into the bowl.
Take the dough out of the refrigerator, and cut it into 6 equal portions. Taking one piece at a time, roll the dough out into a very thin rectangle about 10 to 12 inches. (It's okay if there are holes.)
Layer a spoonful of the scallion mixture over the dough surface. Starting from the end closest to you, roll the dough into a long log.
Stretch out the rolled log to at least 15 inches. Coil the log so it looks like a cinnamon bun.
Roll out each coiled piece of dough into a ¼-inch thick circle.
Place each circle in a nonstick pan coated with oil. Heat the pan on medium heat, cover the pan, and cook the pancakes for 3 to 5 minutes on each side. Serve the pancakes while they're still hot.