Heat the oven to 400 degrees F. Unfold the pastry sheets on a lightly floured surface. Cut each pastry sheet into 4 (about 5-inch) squares.
Stir the vegetables, chicken and hoisin sauce in a medium bowl. Spoon about 1/4 cup vegetable mixture on the lower third of each pastry square. Fold 2 sides over the filling and roll up like a jelly roll. Place the filled pastries seam-side down onto a baking sheet. Brush the pastries with the egg and sprinkle with the sesame seeds, if desired.
Bake for 20 minutes or until the pastries are golden brown.
Recipe Courtesy of Pepperidge Farm® Puff Pastry