Combine the flour and salt in a large bowl or the bowl of a stand mixer. Beat together the egg yolks and water, and add to the flour mixture. Use your hands (not the mixer!) to form a shaggy dough, hand-kneading until well-incorporated. Once the dough has formed, knead using a stand mixer with the dough hook attachment or by hand for another 10 minutes, until the dough is relatively smooth. Cover and rest the dough for 2 hours.
Divide the dough into quarters. Use a rolling pin to roll each piece of dough out into a long 5-inch wide rectangle. If you start with this wider sheet, you will ensure that the dough rolls out to the full width of the pasta roller, or about 6 inches (15cm) wide.
Feed through the pasta roller, starting with the thickest setting, and going through each setting one by one until you reach #4 thickness on a KitchenAid pasta roller or #5 thickness on an Atlas pasta roller (about 1.5 mm). Cut the resulting dough sheets into 6-inch (15cm) squares. Dust each side with cornstarch, and stack them. Then cover with plastic wrap until ready to use.
Notes
It’s best to roll out these wrappers when your filling is all ready to go, so that you can assemble your egg rolls immediately!