5 stars based on 3 Reviews
Prep Time: 10 minutes
Cook Time: 15-20 minutes
Leftover prime rib, sliced thin
2 tablespoons butter
1 large Vidalia onion, sliced thinly
4 sandwich rolls, such as ciabatta or sourdough, split lengthwise and toasted
1/4 cup mayonnaise
1/4cup sour cream
3 tablespoon prepared horseradish
1/4 cup baby arugula leaves
In a large skillet over medium heat melt the butter.
Add the onions and cook until golden and caramelized, about 15-20 minutes.
In a small bowl, combine the mayonnaise, sour cream, and horseradish.
Spread generously on each side of the rolls.
On one side of the roll layer prime rib slices, caramelized onions, then arugula.
Top with remaining half of roll.