Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large mixing bowl, combine the pork sausage meat, chopped onion, fresh parsley, Dijon mustard, and ground black pepper. Mix thoroughly until well incorporated.

Thaw the puff pastry sheets until pliable and cut each sheet in half lengthwise to create four long rectangles.

Place a portion of the sausage mixture along one long edge of each pastry rectangle and roll tightly, ensuring the seam is on the bottom.

Brush the tops with beaten egg and sprinkle sesame seeds if desired. Slice each roll into four pieces.

Transfer to the baking sheet and bake for 22-25 minutes or until golden brown and crispy.

Let cool slightly on a wire rack before serving warm or at room temperature.