Clear a clean, flat surface for rolling out your dough. Have extra flour ready for dusting to prevent sticking.
In a large bowl, combine flour and salt. Mix well.
Create a well in the center of the flour mixture. Add the beaten egg, vegetable oil, and about half of the water.
Begin mixing with chopsticks or a fork, gradually incorporating the flour from the sides. Add remaining water as needed until the mixture forms a cohesive dough.
Transfer the dough to your floured surface. Knead for 5-7 minutes until smooth and elastic. The dough should be firm but pliable.
Cover the dough with a damp cloth or plastic wrap and let it rest for 20 minutes. This allows the gluten to relax and makes rolling easier.
Divide the dough into 4 equal portions. Working with one portion at a time (keep others covered), roll the dough as thin as possible on a lightly floured surface. Aim for about 1/16-inch thickness or thinner.
Using a knife or pizza cutter, cut the rolled dough into 3-inch squares. Dust each wrapper with cornstarch to prevent sticking.
Stack your wonton wrappers with a light dusting of cornstarch between each one. Use immediately or store properly.