Cut rolls in half, spread mayonnaise on bottom half. Place in 9x13 baking dish.
Sauté sliced onion.
Place 1-2 slices of roast beef, sautéed onion, and provolone cheese on top of each roll. Put the top half of the bun on.
Melt the butter. Then whisk in the onion soup mix and Worcestershire sauce. Pour over the rolls.
Cover with foil and return to the fridge for 10 minutes or up to two days.
Bake covered at 375 for 20 minutes or until the cheese is melted.
Uncover and cook for 2 more minutes, or until the tops are golden brown.