In a small bowl mix together the mayonnaise and horseradish to make a sauce.
Spread the horseradish sauce on the bread and pile the prime rib in top.
If desired, top with sauteed mushrooms and sprinkle with parsley.
Serve with au jus for dipping and enjoy!
Notes
expert tips
When you are lucky enough to have prime rib leftovers, making sandwiches is a breeze. Here are some tips to make it extra easy!
Slice up your prime ribafter dinner and store it in an airtight container in the refrigerator so they are ready for sandwiches the next day!
Whip up your horseradish sauce in advance as well!
Reserve some au jus from dinner to use with the sandwiches.
Take prime rib out of the refrigerator 30 minutes before serving to come to room temperature.
You can either heat up the prime rib carefully in a 200-degree oven in a covered baking dish for 10 minutes. Alternatively, I like to serve it at room temp with hot au jus for dipping.Assemble sandwiches and enjoy!