Prepare your kettle braai for indirect heat using 50-60 briquettes - light them and wait 15 minutes until they are ashed over. In the meantime, prepare the meat for the fire.
Place the pork on a clean board or platter, then season generously on all sides with salt, pepper and smoked paprika.
Use a pastry brush to baste the surface all over with mustard, then sprinkle with the chopped rosemary.
Place the pork directly over the hot coals for a quick grill on both sides (about 2 minutes a side), then transfer the pork to the indirect heat position and cover the kettle braai with a lid, vents open.
Roast for 1 hour, then test the inner temperature with a thermometer - it is ready when it shows 75-80° C. Remove from the heat and let the meat rest, covered, for at least 10 minutes before carving.
Serve with the mustard sauce on the side and your choice of salads.
Prepare the sauce: Stir all of the ingredients for the sauce together and serve at room temperature.