French Dip Recipe

Prepare prime rib

If using refrigerated sliced prime rib, let it come to room temperature for 10–15 minutes. Season lightly with 1/2 tsp kosher salt and 1/4 tsp black pepper. If using warm pan-roasted leftovers, slice thinly and rewarm gently in a skillet with a tablespoon of au jus or beef broth over low heat until just heated through (2–4 minutes).

Toast rolls

Preheat oven to 375°F (190°C) or heat a skillet over medium. Split each roll lengthwise without cutting through. Spread about 1/2 tbsp softened butter on each cut side. Place rolls cut-side up on a baking sheet and toast in oven 5–7 minutes until golden and slightly crisp. Alternatively, toast in a skillet 2–3 minutes per side until golden.

Assemble and melt cheese

Arrange equal portions of warmed shaved prime rib onto the bottom halves of the toasted rolls. Top each portion with one slice Swiss and one slice Provolone. Place assembled open sandwiches under a broiler or in a 375°F oven for 2–4 minutes until cheese is melted and slightly bubbling. Watch closely to avoid burning.

Add haystack onions

If using pre-made crispy haystack onions, sprinkle about 1/4 cup per sandwich (adjust to taste) on top of the melted cheese. If frying thin-sliced onions: heat 1 cup vegetable oil in a heavy skillet or pot to 350°F (175°C). Fry small batches of thinly sliced onion until golden brown and crisp, about 1–2 minutes; drain on paper towels and season immediately with remaining 1/2 tsp kosher salt. Use about 1/4 cup crispy fried onions per sandwich.

Finish sandwich

Place the top roll over the onion-topped bottom half. Serve each sandwich with a warmed cup of au jus for dipping. Provide a spoon so diners can spoon extra jus over the meat if desired.

Combine 4 cups beef au jus (or 3 cups au jus/concentrate + 1 cup beef broth) and 1/4 cup dry red wine in a medium saucepan over medium heat.

Add 1 tsp Worcestershire sauce and 1 tbsp butter. Bring to a gentle simmer, stirring to dissolve any concentrated bits. Taste and adjust seasoning with remaining black pepper and salt as needed.

If you prefer a slightly thicker jus, mix 1 tsp cornstarch with 1 tbsp cold water to make a slurry. Whisk the slurry into the simmering jus and cook 1–2 minutes until slightly thickened. Keep warm on very low heat until serving.

If you have pan drippings from roasting prime rib: deglaze the roasting pan with 1/4 cup red wine over medium heat, scrape up browned bits, then add to the saucepan and proceed as above.

Sautéed mushrooms: Heat 1 tbsp butter or oil in a skillet over medium-high heat. Add 3/4 cup sliced mushrooms, season with a pinch of salt and cook 4–6 minutes until browned and any liquid has evaporated. Spoon mushrooms over the warmed prime rib before adding cheese (or add on top of melted cheese).

Caramelized onions: Heat 1 tbsp butter and 1 tsp oil in a skillet over medium-low. Add 3/4 cup sliced onions and a pinch of salt. Cook slowly, stirring occasionally, 20–25 minutes until deep golden and sweet. Add caramelized onions to the sandwich either under the cheese before melting or on top after melting (adds about +1.5 cost).