Line a large sheet pan with a piece of parchment paper and then lightly dust it with cornstarch. Set aside.
Lightly dust the counter with flour and roll the dough into a thin sheet that is almost see-through. I ended up rolling mine into an oval shape that was about 18 inches by 14 inches to give you a rough idea of the size it should be.
Cut circles out of the dough using a ring mold. Alternatively, you can turn a cup upside down and use it as a cookie-cutter. If the cup isn't "sharp" enough, you may have to cut the dough around it with a small knife. *I used a cup, and it gave me 3 1/2 inch circles, which was the perfect size.
Set the circles of dough onto the sheet pan that is dusted with cornstarch. Lay a piece of plastic wrap on top to prevent them from dry out.
Take the dough scraps and knead them together to form a new ball. Re-roll it out and cut out as many more circles as you can.
Now, working with one dough circle at a time, place it in the middle of one of your non-dominant hand and place about 1 tablespoon of filling into the dough's center. Lightly wet one-half side of the dough's edge with water and then form the dough into a taco-like shape. Before sealing the two edges together, form ONE side's edge into a ribbon-like pattern while pressing it up against the other half side at the same time. So, the dough's edges should be sealed together now, but one edge should have a ribbon-like pattern, and the other edge should be flat. ALTERNATIVELY, you can press the outer edges together and skip making the ribbon-like pattern to avoid the hassle. I HAVE PROVIDED A SHORT DEMONSTRATION VIDEO ON THIS TECHNIQUE ABOVE THE RECIPE.
Place the sealed potsticker back onto the sheet pan. Fill and shape all of the dough before moving on to the next step.