Prepare the pork: Pat the pork loin dry and season with salt, pepper, garlic powder, and onion powder.
Sear the pork: Heat avocado oil in a skillet over medium-high heat and sear the pork for 2-3 minutes per side.
Assemble in the slow cooker: Place sliced onions at the bottom, add the pork, and pour in chicken broth and soy sauce.
Slow cook: Cover and cook on low for 4-5 hours or on high for 2-3 hours, until tender.
Make the sauce: In a small pan, melt butter, then add balsamic vinegar, honey, and garlic. Simmer for 2-3 minutes.
Glaze and serve: Pour the sauce over the pork, slice, and serve warm with your favorite sides.