In a bowl, mix together the beef broth, Worcestershire sauce, salt, pepper, Italian seasoning and chopped garlic. Set aside.
Add the sliced sirloin steak, sliced peppers and sliced onions to the bottom of the crockpot.
Pour the beef broth mixture over the top of the meat and vegetables. Stir well to combine.
Cook on low for 7-8 hours or until the meat is tender and cooked through. You can also cook on high for 3-4 hours, but the meat may be a bit tougher.
Turn on your oven’s broiler.
Spread butter on the open side of the hoagie buns and place them buttered side up on a baking sheet. Place the buttered buns under the broiler in your oven until they are toasted and golden. Watch them carefully because they’ll brown up quickly.
Take out the buns and fill each bun with the beef and vegetable mixture. Place a slice of provolone cheese over the top of the meat and return to the broiler for another minute or until the cheese has melted.
Remove from the broiler and close the sandwiches.