Can I make the au jus from scratch instead of using a packet?
Yes. Combine 2 cups beef broth with 1 tablespoon soy sauce, 1 teaspoon Worcestershire sauce, and ½ teaspoon garlic powder. Warm in a saucepan for 2–3 minutes.
Should the roast beef be heated before assembling?
Yes, briefly warm the sliced roast beef in a skillet or add it to the hot au jus for 1 minute so it stays tender and warm when served.
Can I use a different cheese?
Yes. Swiss, American, or mozzarella work well. Provolone's mild, slightly tangy flavor complements the beef, but any melting cheese will work.
How do I prevent the toast from getting soggy?
Assemble the sandwiches just before serving, or serve the au jus on the side for dipping rather than pouring it over the toast.
Can this be made ahead?
Prepare the au jus ahead and store it in the fridge. Toast and assemble the sandwiches fresh to maintain crispness.