Sift flour into a large bowl and make a well in the centre. Whisk together egg, salt and ¼ cup water. Pour into flour well. Mix together, adding additional water until the mixture will stay together in a ball. (You may need more or less then ½ cup, use your discretion. Keep in mind that you do not want it to be sticky.)
Knead the dough until it becomes smooth and pliable.
Let rest for 30-60 min. (This is so the gluten can relax. The longer it sits the easier it will be to roll out)
Divide dough in half. Keep one half covered while you roll out the other one on a surface lightly coated with cornstarch (if you use flour it may toughen it up). Roll out as thin as you possibly can.
Cut into 3.5 inch squares (You should be able to get approx. 12 wonton wrappers out of each half).