Place the beef in a slow cooker. Add water over the top. Sprinkle the dry Italian-style salad dressing mix, Italian seasoning, salt, pepper and garlic powder over the top of the roast. Cover and cook on LOW for 10-11 hours or on HIGH for 5-6 hours or until the beef shreds easily.
Remove the beef from the slow cooker and shred with 2 forks. Place meat in the rolls and top with a slice of cheese. Place the sandwiches on baking sheets and broil 2-3 minutes or until the cheese is melted.
If desired, strain the juices in the slow cooker and serve as a sandwich dip or drizzle juice over sandwich. Top with onions, roasted peppers and/or sliced pepperoncini, if desired.