1. For marinade, in food processor, add celery, rosemary, garlic, olive oil, cayenne pepper, black pepper, and Worcestershire sauce.
2. Drop vinegar, no salt seasoning, and salt in it. Blend well.
3. Place pork on a plate, pour marinade on it, and rub to coat well. Allow it to rest for a couple of hours or until the meat comes to room temperature.
4. Place a skillet on medium high heat, pour olive oil and drop roast in it. Sear roast on both side.
5. In slow cooker pot, throw onion, and add roast. Pour remaining marinade, if any left on plate.
6. Add bouillon cube, seasoning, cayenne pepper, black pepper, and salt.
7. Pour Worcestershire sauce and water.
8. Cover it with lid, and cook on high setting for 6 hours.
9. Serve pot roast hot and enjoy.
You may use 1 ½ liters of chicken stock instead of bouillon cube and water.
Cover everything in pot with water leaving the top of roast.
Cook for 9 hours if using low setting.