Leftover prime rib can be used in a variety of dishes, from breakfast to dinner. Here are some ideas from the search results:

1. Sandwiches: Make a leftover prime rib sandwich topped with caramelized onions, a dollop of sour cream, and au jus for dipping. You can also make a Reuben sandwich by replacing the pastrami with thinly sliced prime rib.

2. Salads: Add thinly sliced prime rib to a steak salad, served cold or warm.

3. Pasta: Make leftover prime rib pasta by heating olive oil in a skillet, adding sliced mushrooms and butter, and cooking until tender. Then, add the sliced prime rib and heavy cream, and cook until heated through. Serve over penne pasta or pasta of your choice.

4. Stir-fry: Add sliced or cubed prime rib to a stir-fry with vegetables.

5. Soup: Use leftover prime rib to make beef barley soup or chili.

6. Pho: Make Instant Pot pho using leftover prime rib.

7. Bone broth: If your prime rib came bone-in, save the bones, roast them, and turn them into bone broth. Use it to make soups or just as an on-its-own sipper.

8. Tacos: Make prime rib tacos by adding sliced prime rib to tortillas with your favorite toppings.

9. Beef stroganoff: Make beef stroganoff with leftover prime rib by adding sliced or cubed prime rib to the creamy stir-fried vegetables in the last few minutes of cooking so that it fully reheats without becoming tough and chewy.

10. French dip: Make a French dip sandwich using leftover prime rib.

Remember to store leftover prime rib in the refrigerator wrapped tightly in plastic wrap or foil or stored in an airtight container. It can last between 5-7 days in the refrigerator or up to 1 month in the freezer.