Preheat oven to 350°F (175°C). Season the beef roast with salt and pepper. Place in a roasting pan. Roast for about 1.5 hours, or until it reaches desired doneness. Remove from oven and let it rest before slicing.

Make the Au Jus

In a large pot, combine beef broth, soy sauce, garlic cloves, sliced onion, black peppercorns, and bay leaves. Bring to a simmer. Add the sliced roast to the pot. Let it simmer for 30 minutes to absorb the flavors.

Prepare the Roasted Garlic Aioli

Make the Aioli

In a small bowl, combine mayonnaise, roasted garlic cloves (mashed), and a pinch of salt and pepper. Mix well and set aside.

Assemble the Sandwiches

Build the Sandwich

Slice the pretzel buns in half. Spread a generous amount of roasted garlic aioli on the bottom half. Layer with sliced beef, sautéed mushrooms, and provolone cheese. Top with the other half of the bun.

Serve

Serve the sandwiches with a small bowl of au jus for dipping.