This recipe comes from long practice and much experimentation. A year in China taught me the basics, and then I started modifying it at home until I was really satisfied with the results. Do not add more water until it is absolutely necessary. Add remaining water as slowly as possible in order to get as hard a dough as you can. If the dough is too soft, add more flour.
Harder dough is much easier to fill.
Chill while you make the filling. Separate dough into 2 portions. Form into long sausages, about 1 inch diameter. Cut sections every 1cm. Form sections into balls and use rolling pin to form into round, flat skins about 3 inches diameter.