Mix together all the marinade ingredients in a large, non-metallic bowl until smooth. Add the pork and mix until well coated. Cover and leave to marinate at room temperature for 15 minutes.
Meanwhile, make the coleslaw. Mix together the vinegar, piri-piri sauce or marinade, sugar and mayonnaise in a small bowl. Toss together the cabbage, carrots and spring onions in a large bowl, then add the dressing and mix together until well combined. Season with salt and pepper and set aside.
Thread the pork on to 8 metal skewers and cook under a preheated grill for 7–10 minutes, turning occasionally, until cooked through and sticky. Serve 2 skewers per person with the coleslaw and steamed white rice, if liked (remembering to count the extra calories).