01 -
Lightly grease a 6- or 8-quart slow cooker with cooking spray. Arrange sliced onions evenly in the bottom of the cooker.
02 -
Pat pork tenderloins dry using paper towels. Season all sides generously with salt and freshly ground black pepper.
03 -
Heat olive oil in a large skillet over medium-high heat. Sear each tenderloin on all sides until golden brown, about 2-3 minutes per side.
04 -
Transfer seared tenderloins on top of the bed of onions in the slow cooker.
05 -
Pour beef broth around the tenderloins without washing off the seasoning. Evenly sprinkle the pork gravy mix over the top.
06 -
Distribute sliced butter on top of each tenderloin. Cover and cook on low for 2 to 2.5 hours, or until the internal temperature reaches at least 145°F and onions are tender.
07 -
Remove pork from slow cooker and slice. Serve immediately with the cooking juices as gravy.