Pat the pork completely dry and season all over with the sea salt and black pepper.
Heat the avocado oil in a large skillet over medium-high heat until shimmering.
Sear the pork in batches, 4 to 5 minutes per side, until a deep brown crust forms.
Transfer the pork to the slow cooker.
No-sear shortcut: Skip searing the pork and sautéing the onion and garlic if needed. Add them directly to the slow cooker, whisk together the Dijon, broth, apple cider, and applesauce, and pour over the pork. Cook as directed, adding the apple and onion wedges during the last hour. Searing adds extra flavor, so do it when you have time!