BLESS THIS MESS
Mix together the salt, rosemary, celery seed, black pepper, and minced garlic in a small bowl. Rub the pork all over with the olive oil and then coat it well with the spice mixture on all sides.
Place the sliced onion on the bottom of the slow cooker, favoring one side of the slow cooker, and then place the pork on top of the onion. Gently drizzle the soy and Worcestershire sauce over the pork. Use a large piece of foil to make a pocket for the potatoes next to the pork.
Fill the foil with the cubed potatoes and add 1 tablespoon of butter. The pork should be off to one side but not completely touching the side of the slow cooker. Add the lid and cook for 3.5 to 4 hours on LOW or until the pork registers 145 degrees
When the pork is cooked through, remove from the oven and allow to rest for 3 minutes. While the pork is resting, place the potatoes in a large bowl and add the remaining 2 tablespoons of butter, chopped parsley and salt to taste.
Slice the pork and place it on a serving platter. Serve right away with buttered potatoes on the side.