Charcoal/gas/electric grill: Grill the pork over/on a medium heat (approx. 200 °C for approx. 2 mins. on each side. Grill the rolls alongside for approx. 2 mins., season the pork.
Combine the ketchup and mayonnaise, spread onto the rolls. Place the pork on the bottom half of each roll, cover with the top half and press down gently.