Preheat the oven to 200°C. In a large mixing bowl, combine the pork mince, French onion soup mix, ketchup, Worcestershire sauce, and Dijon mustard, seasoning generously with black pepper. Divide each pastry sheet into two equal halves. Place a portion of the prepared meat mixture along the center of each pastry strip, shaping it into a compact log. In a separate small bowl, whisk together the egg and milk. Brush this egg wash along one edge of each pastry strip beside the meat, then roll the pastry over the filling, sealing the edge securely. Coat the top of each roll with the remaining egg wash. Using a serrated knife, cut each filled pastry log into 6 to 8 evenly sized segments. Arrange the rolls on a baking tray lined with parchment paper.

Bake for 20 to 25 minutes, or until the pastry turns golden and the filling is fully cooked through.