Rub the spice rub into the pork and leave to marinate overnight in the refrigerator. Return the pork to room temperature for 1 hour before cooking.
Make the coleslaw when you are ready to cook. Put the cabbage, carrots and onion in a colander and sprinkle with the salt, sugar and vinegar. Stir well, then leave to drain over a bowl for 30 minutes. Squeeze out any excess liquid from the vegetables and place in a large bowl. Mix the mayonnaise into the cabbage mixture and season with pepper to taste. Set aside until required.
Cook the pork by the indirect grilling method (see