Cut the pork up into 1 inch squares and place in a resealable freezer bag.
Mix the remaining ingredients together in a small mixing bowl. Pour the marinade into the bag with the pork and seal the bag. Swish the marinade over the pork until all the pieces are well coated. Place the pork in the refrigerator for a minimum of 2 hours. You can let this marinade overnight if you wish.
Mix all the sauce ingredients together in a small bowl and set aside in the refrigerator.
Prepare the grill to medium high heat. Skewer the pieces of pork and onion alternately onto the bamboo skewers.
Grill the skewers for 7 to 9 minutes per side or until all the pink is gone. If you have any marinade left over you can brush some on during the last 5 minutes of cooking. Be sure to discard any leftover marinade.
Remove the pork from the skewers and top with the sauce. The souvlaki is traditionally served in warm pita pockets. Personally, I prefer it served over a bed of rice.