Remove the pork loin from the packaging and pat dry with a paper towel.
You do not need to remove all the fat, but you do want to trim off any silver skin that won't render during the cooking process.
Next, Rub down the pork loin with mustard. You can also use olive oil. this is just to help the rub stick to the meat while it's smoking. Make sure to coat all sides including the ends.
Season liberally with your favorite rub. You want to make sure to have an even coating of seasoning over the entire pork loin. it may seem like a lot of seasoning, but its a thick cut of meat, and the only flavor is on the outside surface.
Place the pork loin back in the fridge for 30 minutes to let the rub set up. the colder the pork loin the better the smoke ring and it also has a little more time to pick up the smoke flavor during the short cook.
Place the pork loin on the pellet grill set at 275 degrees F. Shut the lid and set a timer for about 90 minutes. You are looking for an internal temperature of around 145 degrees F.
Somewhere between 90 minutes and 2 hours depending on the size and thickness, your pork loin will hit 145 degrees F. Now it's time to baste with your favorite bbq sauce. You can also use a glaze or any other sauce you prefer.
Continue to cook for another 15 to 20 minutes until you reach an internal temperature of 150 degrees F. Remove the pork loin from the pellet grill and wrap it loosely in aluminum foil. Rest for 15-30 minutes. (this is important. Otherwise, the pork juices will run out, and the meat will be dry)
Remove the pork from the aluminum foil, Slice the pork loin, and serve