Mix spices together (excluding bay leaf) and set aside.
Place carrots in the bottom of a slow cooker that has been sprayed with non-stick spray (or use a disposable slow cooker liner). Cut potatoes into 1 inch cubes and place on top of carrots. Cut onion into large chunks and add to the slow cooker. Top with bay leaves.
Generously rub roast with the spice mixture on both sides. Place on top of vegetables, pour water or broth over the meat, and cook for 6-8 hours on low.