Heat oven to 375° F.
Using a 2-inch round cookie cutter, cut circles from pastry sheets and place on a baking sheet. Sprinkle with Parmesan and bake until golden brown, about 18 minutes.
Using your fingers, split each puff in half. Spread the bottom halves with mustard and top with thinly sliced salami, lettuce, peppers, and the top halves of the puffs.