Season pork loin with salt and pepper, and place it in a large bowl or ziplock bag.
In a medium mixing bowl, whisk the olive oil, Dijon mustard, soy sauce, thyme, garlic, parsley, and lemon juice.
Pour the marinade over the pork loin and completely coat every inch of the roast.
Let the pork loin marinate for at least an hour or up to 24 hours in the fridge for optimal flavor.
When ready to cook, remove the pork loin from the marinade, shake off any excess, and discard the remaining marinade.
Preheat the smoker to 225℉/107°C.
Place the pork loin in the smoker and close. Smoke for 2-3 hours or until the meat thermometer inserted in the thickest portion registers 145°F/63℃.
For a nice crusty exterior, you can reverse sear the pork loin. Place it in a preheated pellet grill, and cook until the internal temperature reaches 10-15 degrees below your desired temperature. This will depend on your preference, but a recommended internal temperature is around 130°F (54°C).
Remove it from the grill, set it aside, and turn up the heat to medium-high.
Once the grill has reached the desired temperature, transfer the rested pork loin to the hot grill. Sear each side for 1-2 minutes or until nicely browned and caramelized. This step adds a flavorful crust to the pork loin. The ideal internal temperature is 145°F/63℃.
Remove it from the grill and let it rest for at least 10 minutes before slicing. You can garnish it with additional fresh herbs if desired. Serve with desired sauce or as is. Enjoy!