4 cups all-purpose flour, plus more for the surface
1/2 teaspoon salt
About 2 cups boiling water
In a stand mixer fitted with a dough hook attachment, combine the flour, salt and two-thirds of the boiling water. Mix on medium speed while slowly adding the remaining water until well mixed and a ball is formed and the dough is not too hot to handle, 3 to 5 minutes. Sprinkle with a little flour if it gets too wet.
On a floured surface, knead the dough until it becomes a smooth, elastic ball. Place back in the bowl and cover with a damp cloth. Allow to rest for at least 1 hour.
Working on a floured surface with floured hands, roll out the dough to form a long 'noodle', 1-inch in diameter. Cut 1/2-inch pieces and turn them over so the cut sides are facing up. Flatten with your palm and roll out thin using a rolling pin. The dumpling wrapper should end up about 3 inches in diameter.
To make the dumplings: Place a small mound of your choice of filling in the middle of the wrapper. (Be very careful not to touch the edges with the filling as this will impede proper sealing of the dumplings. Nothing is worse than dumplings breaking during cooking.) Lightly brush the top half edge with water and fold the wrapper in half to form a half moon shape. Starting on one end fold/pinch the wrapper tightly together. Proceed with this fold/pinch method until the dumpling is completely sealed. There will be approximately 7 to 10 folds per dumpling. Rest the dumplings with the folded edges straight up, then cook as desired.