Recipes that use leftover prime rib are prime rib soup, prime rib tacos with avocado horseradish sauce and steakhouse prime rib hash. Another recipe is prime rib sandwich with roasted-garlic dijonnaise.
To make a sandwich from leftover prime rib, first whisk together the dijonnaise sauce by placing 6 cloves of peeled garlic, 3 sprigs of rosemary, 1 tablespoon of extra-virgin olive oil and a pinch of salt in a foil pouch. Roast the garlic at 350 degrees Fahrenheit for 30 minutes, and then remove it from the foil. Mash it with 1/4 cup of mayonnaise, 1 teaspoon of Dijon mustard, 1 pinch of salt and 1/2 teaspoon of the olive oil from the foil pouch.
Next, brush the rest of the olive oil from the foil pouch onto 4 halved sandwich rolls, and broil the rolls for 1 minute until they're toasted. Finish assembling the sandwiches by spreading the dijonnaise onto the bread and adding prime rib pieces, sautéed sliced onion and sautéed sliced mushrooms.
Make prime rib tacos with avocado horseradish sauce by blending together 1 avocado, 2 cloves of garlic, 2 tablespoons of lemon juice, 1 teaspoon of prepared horseradish and 1/4 teaspoon of salt. Cook 1/2 sliced onion in 1 tablespoon of olive oil for 3 minutes, and then add 2 cloves of minced garlic and leftover prime rib until everything is warm. Spoon the prime rib and onion mixture onto freshly fried taco shells with the avocado sauce and cilantro.