You could use any grainy mustard, but I had this chipotle dijon in the pantry that I was dying to try. I smeared a very thin layer on the frozen puff pastry.
Bake at 250 for 10-15 minutes, until the pastry begins to brown and puff up. Slice and enjoy this simple appetizer, it is sure to whet your pallet for dinner.
Another puff pastry appetizer that I just loves is from Ina Garten, check out this Goat Cheese and Onion Tart.