Heat butter in a large skillet over medium heat. Sauté sliced onions for 6–10 minutes until caramelized.

Add more butter and olive oil, then add shaved beef in a single layer. Cook for 1–2 minutes on each side until browned.

Return the caramelized onions to the skillet, add Worcestershire sauce and hot sauce, and mix together for 1 minute.

Layer provolone cheese over the beef and onion mixture, cover the pan, and let melt for 1 minute.

Butter the cut sides of the rolls and toast them in the skillets until golden brown, about 2-3 minutes.

Assemble the sandwiches by filling the toasted rolls with the beef and cheese mixture and serve hot.