Prime Rib Sandwich

Prep: 10 mins

Cook: 15 mins

Difficulty: Intermediate

Servings: 4 Servings

I may or may not have a light obsession with beef sandwiches. I have pitched some version of a beef sandwich to be included in every single cookbook I have ever worked on, and I grew up eating steak sandwiches on a regular basis. My desire for a cheese steak is only exceeded by my fixation on chopped cheese sandwiches. That’s why when the opportunity to develop a recipe for a prime rib sandwich presented itself, I jumped at it.

Ingredients

1 tablespoon olive oil
1/2 medium yellow onion, thinly sliced (about 3/4 cup)
4 medium cremini or white button mushrooms, sliced 1/4-inch thick (about 1 cup)
1 pinch kosher salt, plus more as needed
1/4 cup mayonnaise
1 to 2 teaspoons prepared horseradish
1 clove garlic, finely grated or minced
2 (7 to 8-inch) pieces  soft French bread, or 2 kaiser or hoagie rolls with a crisp crust
8 ounces thinly sliced prime rib
2 to 4 slices provolone cheese
2/3 cup arugula

Instructions

Arrange a rack in the highest position of the oven. Heat the oven to broil.
Heat 1 tablespoon olive oil in a medium skillet over medium-high heat until shimmering. Add 1/2 thinly sliced medium yellow onion, 4 sliced medium cremini mushrooms, and 1 pinch kosher salt. Reduce the heat to medium-low and cook, stirring occasionally, until the vegetables are softened and browned, 8 to 10 minutes. Transfer to a small plate or bowl.
Stir 1/4 cup mayonnaise, 1 to 2 teaspoons prepared horseradish, and 1 finely grated garlic clove together in a small bowl. Taste and season with kosher salt as needed. 
Split 2 pieces soft French bread in half lengthwise. Spread the cut sides with the horseradish mayo.
Place the bottom halves of the bread cut-side up on a baking sheet. Top with 8 ounces thinly sliced prime rib, the onions and mushrooms, and 2 to 4 slices provolone cheese (a single layer). Broil until the cheese is melted, 1 to 2 minutes. 
Top the sandwiches with 2/3 cup arugula, and close each sandwich with the top half of the bread.