Corn syrup gives these cookies added crispness and a shiny glaze.
Heat oven to 425 degrees. Defrost pastry according to the manufacturer's directions. Line two baking sheets with parchment, and set aside.
Sprinkle a clean work surface with 1/4 cup sugar. Place dough over sugar, and sprinkle with remaining 1/4 cup sugar. Using a rolling pin, gently press sugar into dough, rolling out dough slightly; rotate dough frequently to prevent sticking. With longer side of dough toward you, fold over edge, and roll tightly with your hands until you reach the middle. Turn dough so the unrolled edge is toward you, and roll again, meeting first roll in center.
Chill dough in freezer 15 minutes. Cut into 1/4-inch-thick slices, and place on prepared baking sheets.
Bake the palmiers 7 minutes. Meanwhile, in a small bowl, combine corn syrup with 1 tablespoon water. Using a pastry brush, lightly brush palmiers with corn-syrup mixture; bake another 4 minutes. Turn the cookies over, and brush with syrup again. Continue baking until golden brown, about 4 minutes more. Transfer palmiers to a wire rack to cool completely, and store in an airtight container for up to 1 week.