Step 1: Butterfly the pork loin: Place the pork loin on a cutting board. Using a long, slender, sharp knife, cut the loin almost in half lengthwise through one side. Open up the loin as you would a book. Lay a sheet of plastic wrap on top and pound it with the side of a cleaver to flatten it slightly. Season the inside with salt and pepper and spread with mustard.

Step 2: Arrange the pastrami over one side of the pork loin, followed by the sauerkraut and cheese slices. Fold the roast back together (like closing a book).

Step 3: Position the six 12-inch pieces of butcher’s string on your work surface so that the strings are parallel and roughly 2 inches apart. Lay 2 bacon slices across the strings so that they run perpendicular to and in the center of the strings. Set the pork loin on top of the bacon running perpendicular to the strings. Place 2 slices of bacon on top of the loin. Press the remaining 2 slices against the long sides of the loin.

Step 4: Bring the end strings, then the middle strings, over the roast to tie it back into a tight cylinder and hold the bacon slices against it. Breathe a sigh of relief: the hard part is over. The pork loin can be stuffed several hours ahead to this stage.

Step 5: Set up the grill for indirect grilling and preheat to medium. Brush or scrape your grill grate and oil it well.

Step 6: When ready to cook, place the pork roast on the hot grate, over the drip pan and away from the heat, and cover the grill. Cook the roast until cooked through, 1 to 1 1/2 hours. To test for doneness, insert an instant-read meat thermometer into the center of the roast: The internal temperature should be about 155 degrees. Transfer the cooked roast to a cutting board and let it rest for 5 minutes, then remove and discard the strings. Cut the pork loin crosswise into 1/2 inch thick slices and serve with the Russian Dressing.