Rub all sides of the pork with mustard. Tip: you won’t taste the mustard after it’s smoked, but if you don’t like mustard, you can use olive oil as a binder instead.
Now sprinkle the seasoning rub all over the pork loin and pat it in with your hands.
Place the seasoned pork loin directly onto the smoker grill grates. Close the lid and smoke for 2 to 2 1/2 hours. It can take up to 3 hours to fully cook this pork depending on the thickness of the meat. Cook the pork until the internal temperature reaches 145 degrees F. Use a meat thermometer to check the internal temperature of the meat.
Transfer the roast from the smoker to a large plate or cutting board and cover with foil. Let it rest for 10-15 minutes, then slice against the grain and serve.