Sift flour and salt into a large bowl. Make a well in the center and add egg and water. Stir with fork until dough holds together and leaves sides of bowl clean.

Turn out dough onto lightly floured surface; knead until smooth and elastic, about 5 minutes.

Cover dough with a bowl. Allow dough to rest at least 30 minutes.

Divide dough into fourths. Dust pastry board lightly with cornstarch. Roll each piece of dough to a 14X11 inch rectangle. Cut into 3-1/2 inch squares. Stack on a plate. Cornstarch will prevent them from sticking together. Fill with filling.