Combine cornstarch with 1/3 cup sugar; add to skillet. Stir in peaches, cinnamon and salt. Cook until mixture thickens and boils, about 25 minutes, stirring frequently. Boil for one minute; remove from heat and stir in lemon juice. Cool completely; set aside.
Cut crusts into quarters; spoon 2 tablespoons filling into the center of each quarter, leaving 3/4-inch dough uncovered on each side. Fold dough over filling; press edges together to seal.
Transfer pies to 2 ungreased baking sheets.
Brush tops of pies with egg; sprinkle with remaining sugar.
Cut a one-inch slit in the top of each pie.
Bake at 425 degrees for 18 to 20 minutes until golden, rotating baking sheets between upper and lower racks halfway through baking.