- Preheat oven to 450°F. 
- Butterfly the pork. With the pork on a cutting board, hold a knife bald parallel to the board and carefully make a lengthwise cut about 1/3 of the way from the bottom, stopping about 1 inch from the opposite end, being careful not to cut through. 
- Open the loin like a book. 
- Make a second cut on the thick side of the pork loin, horizontal with the first cut. Do not cut all the way through, stop about 1 inch from the opposite edge. Fold that edge over making one long cut of pork loin. 
- Cover the entire cut of meat with plastic wrap and pound to an even ⅓ inch thickness. 
- In a small bowl, combine oil, salt, garlic, and parsley.  Rub over both sides of pork loin. 
- Top the pork loin with mustard, ham, pickles and swiss cheese. 
- Tightly roll the pork loin to completely enclose all of the fillings. 
- Using cooking twine, tightly secure the roll. 
- In an oven-safe skillet, over medium heat, add a tablespoon of olive oil and the pork loin to the pan and sear on all sides (about 5 minutes on each side), turning the loin a total of 4 times. 
- Transfer the skillet to the oven and cook for 35-40 minutes or until the pork loin reaches an internal temperature of 145 °F.  Occasionally baste the pork loin with the pan juices. 
- Slice and serve warm.