• Thinly slice your leftover prime rib and allow it to sit at room temperature while you prepare the other ingredients.

For the mushrooms:

• Heat the oil in a pan over medium high heat. Add the mushrooms, spreading them evenly over the pan. Cook, undisturbed, for several minutes or until browned. Flip and continue to cook an additional minute or two, adding the garlic for the last 30 seconds. Sprinkle with salt to taste.

For the au jus:

• Add the beef drippings to a sauce pot and heat over medium high heat. Once it is simmering, whisk in the flour until the mixture is smooth and bubbly.
• Slowly drizzle about ¼ cup of the beef broth into the flour mixture. It will bubble quite violently! Once it’s settled a bit, drizzle the rest of the broth in. Continue to cook until mixture is gently boiling and slightly thickened, another few minutes.
• Stir in Worcestershire and soy sauce. Remove from heat, then taste and season with salt and pepper as needed.

For the sandwiches:

• Broil the garlic bread. Mix together the butter and garlic cloves in a small bowl. Slice the rolls and slather the butter mixture evenly over both sides. Place them on a pan, butter side up, and broil for about 2 minutes, until brown and toasty.
• Broil the meat and cheese. Take the bottom of each roll and stack each of them with half the prime rib, followed by the sliced cheese. Place the sandwiches back under the broiler for another 1.5-2 minutes, or until cheese is melted.
• Add toppings. Top the sandwiches with the sliced peppers, mushrooms, and the second garlic bread. Serve with warm au jus.