Prime Rib Recipe

Warm and slice

If your smoked prime rib is refrigerated, bring it to room temperature for 20–30 minutes. Reheat gently: place slices in a single layer on a sheet pan, cover loosely with foil, and warm in a 300°F (150°C) oven for 8–12 minutes until just warmed through. Keep juices on the pan to use in au jus.

Toast the baguette

Slice the baguette lengthwise. Brush cut sides with 2 tbs unsalted butter melted. Place cut-side up on a sheet pan and toast in a 400°F (200°C) oven 6–8 minutes until golden and crisp. Remove and keep warm.

Assemble sandwiches: spread a generous layer of horseradish aioli on both cut sides of the toasted baguette. Layer warmed shaved prime rib evenly on the bottom half, spoon caramelized onions over the meat, top with provolone slices (3 per sandwich half; adjust to size). Close sandwich, press lightly and cut into portions.

Heat 1 tbs olive oil and 1 tbs butter in a large skillet over medium-low heat. Add the sliced onions, 1 tsp salt, 1 tsp black pepper and 1 tsp sugar. Cook slowly, stirring every 3–5 minutes, for 25–35 minutes until onions are deep golden brown and sweet. If they begin to stick, add a splash (1–2 tbs) water or a teaspoon of beef stock to deglaze. Remove from heat and keep warm until assembly.

Whisk together 3 tbs mayonnaise, 2 tsp prepared horseradish, 1 tsp Dijon mustard, 1 tsp lemon juice, 0.5 tsp minced garlic, 0.25 tsp salt and 0.25 tsp black pepper in a small bowl. Taste and adjust horseradish for heat. Chill in refrigerator at least 15 minutes to let flavors meld. Use as spread for both sides of the baguette.

Deglaze & simmer: In a small saucepan over medium heat add 2 tbs dry red wine (if using) and scrape any browned bits from the prime rib sheet pan or carving board. Add 2 cups beef stock, 0.25 cup beef drippings/pan juices, 1 tsp Worcestershire sauce and one thyme sprig. Bring to a gentle simmer and reduce 6–8 minutes to concentrate flavor slightly.

Finish & season: Remove thyme sprig. Whisk in 1 tbs cold unsalted butter to lend body and sheen. Season to taste with 0.25 tsp salt and 0.25 tsp black pepper. Keep warm and serve in a small bowl alongside the sandwich for dipping.