Instructions

1. Cut the pork into large cubes.
   
2. In a small bowl, combine the mayonnaise and mustard, mixing well.
   
3. Peel the onion and cut it into rings about 1-1.5 cm (about 1/2 inch) thick.
   
4. Place the onion rings at the bottom of a container. Add the pork on top, then pour the mustard and mayonnaise marinade over the pork. Mix to coat the pork well, stirring gently to avoid breaking the onion rings.
   
5. Cover the container with a lid and refrigerate for 8-12 hours (I usually leave it for a whole day).
   
6. If using wooden skewers, soak them in water for an hour before cooking.
   
7. Thread the marinated pork pieces and onion rings onto the skewers and grill them a little distance from the coals, turning occasionally, until cooked through.