Prepare the dough: In a stand mixer, combine gluten free flour, xanthan gum, tapioca starch, and salt. Mix to combine on low speed. Add the egg and mix for 1 minute.
Once combined, add the water 1 tablespoon at a time until the dough is smooth. Mix on medium speed for 2 minutes.
Test to be sure dough is ready by squeezing it with your hands. If it holds together it is ready. If it crumbles, add more water.
Remove from the stand mixer and form into a ball. Place onto a piece of plastic wrap. Wrap the dough and set aside for 15 minutes.
Prepare the filling: While the dough sets, prepare the filling. Finely dice the carrot, white onion, and celery stalk.
Chop napa cabbage into thin strips. Add all ingredients to a large mixing bowl and stir together with a wooden spoon.
Roll out the dough: Remove dough from plastic wrap and set on a floured surface. Place a film of plastic wrap over the dough. Roll out to 1/8” thick (or thicker if you like). Use a 3” biscuit cutter to cut out circles of dough.
Add dough rounds to a parchment or silicone lined baking sheet. Roll up remaining dough pieces into a ball and repeat this step until there are no scraps. This should yield 16 dough rounds.
Assemble the potstickers: Add 1 tablespoon of filling to the centre of each round. Dip your finger in water and trace around the edge of the dough. Fold the dough rounds in half over the filling.
Pinch together the dough in the centre, then crimp the edges and pinch with your fingers to seal.
Whisk the egg for the egg wash in a small bowl. Brush the egg wash over both sides of the potstickers.
Cook the potstickers: Heat a saute pan over medium high heat with 2 tablespoons coconut oil. Add potstickers to the pan flat side down.
Fry for 2 minutes. Turn off heat. Carefully add ¼ cup of water to the pan and cover. Turn the heat back on to medium and steam the potstickers for 5 minutes.
Make the sesame sauce: While the potstickers are steaming, prepare dip. Add all ingredients to a small mixing bowl and whisk to combine.
Serve potstickers with dip and garnish with green onions. Enjoy!