Preheat your oven to 350°F (175°C).
In a large pot, heat a tablespoon of oil over medium heat.
Add sliced onions and cook until soft and caramelized.
Stir in minced garlic and cook for an additional minute.
Pour in the beef broth and Worcestershire sauce, bringing it to a simmer.
Season with salt and pepper to taste.
Add the thinly sliced roast beef to the broth, allowing it to soak for about 10 minutes.
While the beef is soaking, cut the hoagie rolls in half and place them on a baking sheet.
If desired, add provolone cheese to the rolls.
Bake the rolls in the oven for 5-7 minutes until toasted.
Once the beef is heated through, assemble the sandwiches by placing the beef in the rolls.
Serve with a small bowl of au jus for dipping.