Pat pork dry with paper towels.
Combine salt, paprika, onion powder, and black pepper in a small bowl; whisk to combine. Take the rub and sprinkle it all over the pork.
Add 1 tablespoon olive oil in a large skillet and set over medium heat; add pork and sear for a couple of minutes on each side, or until golden brown.
Add chicken broth to the insert of your slow cooker. Place pork loin, fat side up, in the slow cooker and set aside.
In a blender or food processor combine remaining olive oil, balsamic vinegar, and garlic; process until combined and thickened. Add Italian seasoning and whirl for just a couple of seconds to combine. Using a pastry brush, brush the prepared balsamic mixture all over the pork loin.
Cover slow cooker with a lid and cook on LOW for 6 to 8 hours, or on HIGH for 4 to 5 hours.
Remove pork from slow cooker and transfer to a cutting board; cover pork with foil and let rest for 15 minutes before slicing.
Slice and serve.
Bonus tip: If you prefer to use an oven, prepare the pork loin as described then put in the oven at 450 degrees for 20 min or the internal temperature is 145 degrees