In a saucepan, combine the beef broth with the onion and all of the spices (through the salad dressing mix). Stir well, and bring to a boil.
Place the roast in your slow cooker insert. Pour the broth mixture over the roast.
Cover, and cook on low for 8 hours. Pour the jar of pepperoncini (juices and all) over the meat, put the lid back on and cook for an additional 2 hours.
Remove the bay leaf, and shred meat with a fork.
Serve the beef on warmed hoagie rolls. These are delicious with sauteed onions, peppers and/or mushrooms. Add the Swiss cheese and broil to melt. Serve immediately.