Mix together:
450 ml flour
2.5 ml salt
Beat together gently in a small bowl:
1 egg
60 ml water
Make a well in the middle of the flour and add the egg-water mixture. Mix into the flour. Add up to 60 ml more water as needed.
Knead the dough into a ball. Keep kneading until smooth (several minutes) Place the dough in a large bowl, cover with a damp cloth and let rest for 1 hour.
Cut the dough into quarters. Place one of the quarters on a well-floured surface, and roll out with a rolling pin until very thin. Add flour as needed. Cut the dough into 20 cm squares. Set aside and cover with a damp cloth while preparing the remaining wrappers. (If stacking, dust the wrappers lightly with flour or cornstarch to keep them from sticking together).
Repeat with the other quarters. If not using immediately, wrap in plastic and store in the refrigerator or the freezer.