Cut the washed and dried pork meat into pieces. (Neck part is preferable).
Cut the onion into rings, squeeze it to let the juice flow.
Sprinkle the meat with salt and pepper to taste. (Do not forget that mayonnaise is also salty, so don't oversalt the dish). Usually, a little more than half a teaspoon of salt and two teaspoons of a mixture of peppers on a kilogram of pork are though.
Mix the meat with onions, mayonnaise, and mustard.
Cover the container with meat by a lid and let it brew for 4-5 hours in the kitchen. If the picnic is planned for the next day, it is better to send the meat to the refrigerator until the next day.
Bake meat on charcoal, (stringing tightly enough on skewers) until browned on all sides.