Place the carrots, potatoes, and onion in the bottom of the slow cooker and season lightly with salt and black pepper.
Pat the pork tenderloin dry, season with salt and black pepper, then set it on top of the vegetables.
Stir together the honey, minced garlic, soy sauce, and olive oil in a small bowl until smooth.
Pour the honey garlic mixture evenly over the pork and vegetables.
Cover and cook on low for 6 to 7 hours or until the pork reaches 145 degrees and the vegetables are tender.
Remove the pork, let it rest for 5 minutes, then slice it and return the slices to the slow cooker to soak in the sauce.
Sprinkle with chopped fresh parsley just before serving.