I've been making scallion pancakes regularly for a while now
and feel like I have got the recipe dialed in. It's actually pretty close to the one I started with, but I've explored the space of flour ratios, rollouts, fats mixed into the dough or for rolling or for frying, frying temperature, and the precise maximum amount of scallions that a pancake can hold before they escape.
2.5 cups AP flour
1/4 to 1/2 tsp salt, if I remember which a lot of the time I don't
1 cup not quite boiling water
You will need small amounts of flour for each following step, but not nearly as much as if you start with a 2:1 ratio of flour to water as some recipes do.
Mix together in a medium sized bowl with a wooden spoon until it forms a shaggy dough. Knead for five minutes at which point it will be nice and smooth. Rest in the fridge, covered, for at least an hour and usually overnight.
2 cups of scallions (erring on the side of too many).
You will also need at this point:
2 tablespoons duck fat (if you don't have duck fat or want to be vegan, sesame oil also works well)
Divide into six pieces by weight (usually each piece is about 3.25 oz). Roll out each piece (size of the rollout is not critical at this step but I usually aim for 7-8 inches) and brush with 1/2 teaspoon duck fat, leaving the fat off the inch of dough furthest away from you. Roll up and coil each piece, form into a patty, and go on to the next piece before doing the next step (for me, this results in each piece getting a 10-15 minute rest at room temperature).
Re-roll, brush with another 1/2 teaspoon duck fat, and add 1/3 cup scallions, also leaving scallions off the inch of dough furthest from you. Roll up, coil, form into a patty, and refrigerate in a small bag or plastic wrap to rest for another hour or more (but try to use them all up within a day or two, they don't last forever.)
Roll out a final time to a diameter of about 8 inches and fry in canola oil. The hotter the oil, the chewier the pancakes will be.
Still working on measuring the quantities on the dialed-in sauce but it is approximately 1 part sesame oil, 4 parts white rice vinegar, 14 parts tamari, dash of powdered ginger. Honey sauces are nice and all but for whatever reason they are not my sauce.