Pat dry the pork. Cut about ¼ inch down the fat cap in a diagonal patter. Rub the mustard on the pork. Mix all of the spices in a bowl and then rub liberally over the pork.
Preheat smoker to 225°F. Smoke pork until the internal temperature reaches 145°F, about 2-2 ½ hours.
Remove from the smoker and tent with foil, allowing it to rest for about 10 minutes. Slice against the grain and serve.
Notes
While some fat is desirable for flavor, trim any excessive fat to prevent flare-ups and ensure even cooking.
Make diagonal cuts about ¼ inch deep on the fat cap. This aids in rendering down the fat and allows better seasoning penetration.
Use apple wood for smoking. Apple and pork go together like peas and carrots.
If you don't want to make your own spice rub, just use store-bought.
Let the loin rest for 10 minutes before slicing which lets the juices stay inside.
Slice the pork against the grain so it remains tender.