• Preheat your grill with a setup for indirect cooking. Use Smoke X or FRX GATEWAY and Billows to get the internal temperature up to 350°F (177°C) while you prepare the loin. Use some wood chunks for delicious smoked flavor. 

  (For instructions on how to make this recipe in your oven, see our post on Slow-Roasted Stuffed Pork Loin.)

Make the filling

• Chop the bacon and cook it in a large pan over medium heat. You want the bacon to get nice and cooked and to render all of its fat.
• Add the chopped fennel seed and cook in the fat for 15–30 seconds, until quite fragrant and toasty smelling. 
• Drain the leeks well and add them to the pan, sauteing until they are well wilted, and start browning around some of their edges.

  

  

• Add the butter to the pan and cook to melt it.
• Add the chopped mushrooms to the pan and stir, cooking until the mushrooms have cooked out a lot of their water and start to brown around the edges of the pan. 

  

  

• Remove from heat and allow to cool somewhat. 
• Stir in the breadcrumbs, pistachios, and Parmesan cheese.

  

  

  

• Taste and adjust salt and pepper accordingly. 

Butterfly the pork and stuff it

• Lay the pork on the cutting board and make a cut along the length of the loin, 1/2" above the board and parallel to it. Continue this cut through the loin until the knife is about 1/2" from the opposite side of the loin.
• Open the loin like a book; there will be a thick side and a thin side. 
• Repeat this action on the new thick side, unrolling the pork loin as you go. 
• Repeat a third time, if you can. 
• Salt and pepper the surface of the pork loin.
  
• Shingle the prosiutto over the surface of the meat.
• Spoon the mushroom filling onto the surface of the loin. Spread it as needed to cover the loin by about 1/2". You may have extra filling. 

  

• Lay the thin-sliced apples atop the mushroom filling. You may have extra apple slices. 

  

• Roll the pork loin back up. 
• Tie the loin with butcher twine, making a knot about every inch along the length. 

  

  

• Season the exterior of the loin with BBQ rub.

  

Cook the roast

• Place the tied, seasoned roast in the grill and insert the meat probe from your Smoke X or RFX MEAT into the center of the roast. 
  
• Set the high-temp alarm on the meat channel for 140°F (60°C) and cook the roast. 
  
• When the alarm sounds, verify the temperature with Thermapen ONE. If you don't see a temperature lower than 140°F (60°C), remove the roast from the grill and let it rest for a few minutes before slicing it up. If you find any lower temperatures, adjust the position of your meat probe and continue to cook until the true lowest temp in the meat has reached your pull temp. 
  
• Slice the roast and serve.