Making these pancakes requires a little bit of skill, but I will walk you through step by step below. Any sort of green onion will work, from regular green onions to chives, garlic chives, ramps or any wild onion. I use a tortilla press to quickly flatten the pancakes, but you can certainly use a normal rolling pin. These are best served warm, but are almost as good at room temperature.
Put the flour in a large bowl and mix in the salt. Make a well in the center. Bring the water to a boil, then turn off the heat. When the water stops bubbling, pour it into the well in the flour. Stir together with a fork until you get a shaggy mass. Wipe the goopy flour off the fork and knead the mass into an elastic dough, which should take about 3 to 5 minutes. Put the dough into a plastic bag or wrap it in plastic wrap and let the dough sit for 30 minutes to 2 hours.
Take the dough out and cut it into four pieces. Put three of them back into the plastic bag. For a work surface, I use a baking sheet flipped over that I've lightly oiled with vegetable oil. Roll out the piece of dough into a roughly rectangular shape; it doesn't need to be precise.
Paint the dough with the sesame oil, then sprinkle with about a half teaspoon of salt. Sprinkle minced scallions over the dough generously, leaving about 1/2 inch free space on all sides of the dough.
Roll the dough into a tight log starting from the longer side of the rectangle. Slice the log in half and pinch closed the ends of the log to keep the scallions from spilling out. Take one half of the log and roll it tightly into a snail. Flatten the snail with the palm of your hand.
Cut up a Ziploc bag or somesuch into large plastic squares that will cover your tortilla press. Place the flattened snail on one piece of plastic, cover it with another. Squash the dough with the tortilla press, or roll it out with a rolling pin to a thickness of 1/8 to 1/4 quarter of an inch.
Now you need to fry the pancakes in a little hot oil. I fry and press each one as I go, keeping the finished pancakes in a tortilla warmer lined with paper towels. You could also put them on a baking sheet in an oven set to 200°F. But if you are a beginner, roll out all your pancakes first.
I fry the pancakes in a large sauté pan with about a tablespoon of vegetable oil. I prefer peanut oil because it's used a lot in Chinese cooking. Lard is another good choice. Get the oil hot before you drop the pancake in and cook for about 2 minutes per side, just until you get a little browning on them. Serve by themselves, with soy sauce or with a sweet-spicy dipping sauce.
Notes
Scallion pancakes will keep, wrapped in a paper towel, for a day or two in the fridge. They can also be frozen.