Prime Rib Sandwich Recipe

Warm and slice

If the prime rib is chilled, warm briefly to serving temperature: place in a 300°F (150°C) oven for 10–15 minutes until warm but not overcooked. Thinly slice the prime rib across the grain into 1/8"–1/4" slices and season lightly with 1 tsp kosher salt and 1/2 tsp black pepper.

Heat au jus

In a small saucepan over medium heat, melt 2 tbs unsalted butter. Add 1.5 cups beef au jus and bring just to a simmer. Taste and adjust seasoning. Keep warm on the lowest heat setting; cover to retain heat while assembling sandwiches.

If you have rich pan drippings, skim excess fat, deglaze pan with 1/2 cup beef stock or water, and pour into the saucepan to make au jus before warming.

In a medium bowl combine 2 cups shredded green cabbage, 1 cup shredded red cabbage and 1/2 cup grated carrot.

In a separate small bowl whisk together 3 tsp prepared horseradish, 3 tbs mayonnaise, 2 tbs plain Greek yogurt, 1 tsp apple cider vinegar, 1/2 tsp Dijon mustard, 1/2 tsp sugar, 1/2 tsp kosher salt and 1/4 tsp freshly ground black pepper until smooth.

Pour the dressing over the cabbage mixture and toss to coat evenly. Let the slaw rest 10–15 minutes at room temperature to mellow flavors (or refrigerate up to 1 hour). Taste and adjust horseradish or salt as desired.

Prepare the bread: preheat broiler or a salamander to high (or use a hot cast-iron pan). Brush the cut sides of the split baguette with 1 tbs olive oil and spread 1 tbs softened butter on the outer crust if desired. Lightly rub the cut surfaces with the halved garlic clove for a subtle garlic note.

Layer the cheese: Arrange the thinly sliced raclette cheese evenly on the cut surfaces of both bread halves, overlapping slightly so the cheese will melt into a continuous layer.

Gratinée (melt and brown): Place the cheese-topped bread under the broiler 3–5 inches from the element for 2–4 minutes until the raclette is fully melted and lightly browned and bubbly. Watch closely to avoid burning. Alternatively, place the topped bread in a 400°F (200°C) oven for 6–8 minutes or use a raclette melter to melt the cheese.

If using a skillet: warm a cast-iron skillet over medium-high heat, place the bottom half of the bread cheese-side up, cover with a lid and place a heavy pan on top briefly to encourage melting, then remove lid and transfer to a plate when cheese is melted.

Once melted, remove from heat and let rest 1 minute to allow cheese to set slightly before assembling.

Warm the sliced prime rib briefly in the au jus: add the sliced beef to the warm au jus for 30–60 seconds to reheat and coat lightly. Use tongs to lift the slices from the jus, allowing excess to drip back into the pan.

On the bottom half of the raclette-gratinée bread, arrange a generous layer of the au jus–warmed prime rib (about half to two-thirds of the meat). Spoon a tablespoon or two of au jus over the meat for extra moisture if desired.

Top the meat with 2–4 tbs of the horseradish slaw (adjust to taste). Close the sandwich with the top half of the cheese-topped bread.

Optional finishing: press the closed sandwich in a warm skillet for 30–60 seconds per side to seal and compress slightly, or serve open-faced with the top half on the side. Serve immediately with remaining au jus for dipping.

Carve the sandwich into 2–3 portions and pass extra horseradish slaw and au jus alongside.