Heat olive oil in a large skillet over medium heat.
Sauté sliced onions until translucent, about 5 minutes.
Add minced garlic and cook for an additional minute.
Pour in the beef broth and Worcestershire sauce.
Bring the mixture to a simmer, then reduce heat to low.
Season with salt and pepper to taste.
Add the thinly sliced roast beef to the broth, allowing it to warm through.
Slice the hoagie rolls and lightly toast if desired.
Assemble the sandwiches by placing beef inside each roll.
Serve with a small bowl of the warm au jus for dipping.