Preheat oven to 425 degrees. Position a rack in the center of the oven.
Line a rimmed baking sheet with parchment paper. Set aside.
In a small bowl, combine sugar, cinnamon and salt.
Pour a 1/4 cup of the mixture on a work surface. Place puff pastry sheet on top of mixture.
Roll sheet into a 10x14 inch rectangle.
Sprinkle extra 1/4 cup of cinnamon sugar mixture on top of puff pastry.
Use rolling pin to roll over the dough to work in the sugar mixture.
Trim edges to make a perfect rectangle.
Fold long sides of dough into the center of the dough. Then fold over long sides once more. Fold one side over the other side to make a long thin rectangle.
Place the pastry on the prepared sheet and place in the freezer for 15 minutes to firm up.
Take out of the freezer and place back onto sugared work surface and using a sharp knife, slice into 1/4 inch slices.
Place cut side up (as pictured) onto prepared sheet 2 inches apart. Sprinkles each piece with left over sugar from work surface.
Bake for 12 minutes until lightly browned. Remove from oven and flip pastries over and continue to bake for an additional 5-7 minutes until sugar is caramelized.Pay close attention while they are baking for the last few minutes, so they do not burn
Transfer to wire rack to cool.
Pastries will keep in airtight container for 4-5 days.