Dinner · Part 3 of 3: Tips & recipe card

French Dip Prime Rib Sandwiches with Swiss & Horseradish Aioli Tips, FAQ & printable recipe

Name: French Dip Prime Rib Sandwiches with Swiss & Horseradish Aioli
Prep time: 15 min
Cook time: 20 min
Total time: 35 min
Cuisine: American
Ingredients: 400 g thinly shaved prime rib or roast beef; 4 crusty French rolls, split; 8 slices Swiss cheese; 1 large onion, caramelized; 1/3 cup mayonnaise; 1 tbsp prepared horseradish; 1 tsp Dijon mustard; 1 tsp lemon juice; 2 cups rich beef consommé au jus

By Clara Weller · Oct 21, 2026

French dip prime rib sandwich with melted Swiss cheese and horseradish aioli on a crusty roll, dipped in beef au jus.

Prep: 15 min
Cook: 20 min
Total: 35 min
Serves: 4

Tips for success

For the best texture, warm the beef in the jus just before serving, and do not let it sit in the hot liquid for more than a minute.

This keeps it tender and prevents it from becoming overly salty. If you have leftover jus, it can be refrigerated and reused for another batch—just reheat it to a simmer before adding fresh beef.

When toasting the rolls, keep the cut side up and broil on high for a short time. If you prefer a softer roll, skip the toasting and use them as is, but they may become soggy when dipped.

The caramelized onions can be made ahead and stored in the refrigerator for up to 4 days. Reheat them gently before assembling the sandwiches.

Variations

Classic Roast Beef: Use thinly sliced deli roast beef instead of prime rib. Warm it in the jus and follow the same assembly. This is a budget-friendly option that still tastes great.
Spicy Au Jus: Add a pinch of red pepper flakes or a dash of hot sauce to the beef consommé while heating. This gives the jus a subtle kick that pairs well with the horseradish aioli.
Garlic Herb Aioli: Replace the horseradish with 1 clove of minced garlic and 1 tablespoon of chopped fresh parsley. This creates a milder, herbaceous spread for those who prefer less heat.
Mushroom Swiss: Sauté 1 cup of sliced mushrooms with the onions until golden. Add them to the sandwich along with the beef for an earthy, savory twist that complements the Swiss cheese.

Storage and make-ahead

Fridge: Store leftover sandwiches and jus separately in airtight containers in the fridge for up to 2 days. Reheat in the oven.
Freezer: Freeze assembled sandwiches (without jus) wrapped tightly in foil for up to 1 month. Reheat in a 350°F (175°C) oven for 10–15 minutes.
Reheat: Reheat sandwiches in a 350°F (175°C) oven for 5–7 minutes until hot and cheese is melted. Reheat jus on the stovetop until simmering.

Store leftover sandwiches (without the jus) in an airtight container in the refrigerator for up to 2 days. Keep the au jus separately.

To reheat, place the sandwich on a baking sheet and warm in a 350°F (175°C) oven for 5–7 minutes, or until the cheese is melted and the beef is heated through. The bread may lose some crispness, but it will still be delicious.

The horseradish aioli can be made up to 3 days in advance and stored in the refrigerator. Caramelize the onions ahead of time and refrigerate for up to 4 days.

The beef can be shaved and kept refrigerated for up to 2 days. When ready to serve, warm the beef in the jus and assemble the sandwiches. This makes the recipe perfect for entertaining.

Serving ideas

Serve the sandwiches hot, with a small bowl of the beef consommé on the side for dipping. The jus should be steaming and deeply flavored. Pair with a crisp green salad, pickles, or a bowl of tomato soup for a complete meal. For a more indulgent touch, add a side of au jus–soaked fries or a pile of crunchy potato chips.

These sandwiches are best enjoyed immediately after assembling, while the cheese is still molten and the bread is crisp. If serving a crowd, keep the assembled sandwiches warm in a low oven (200°F / 95°C) for up to 15 minutes, but do not hold longer or they will become soggy. Provide extra napkins—this is a hands-on meal.

Frequently asked questions

Can this recipe be made with store-bought roast beef?

Yes, store-bought deli roast beef works well. Look for sliced roast beef that is not too dry. Warm it in the beef consommé for about 30 seconds, just until heated through. The quality of the beef will affect the final flavor, so choose a good brand or ask for a thick slice and slice it yourself.

What is the best way to caramelize the onion?

Thinly slice the onion and cook it slowly in a little butter or oil over medium-low heat for about 20–25 minutes, stirring occasionally, until deep golden brown and sweet. Adding a pinch of salt helps draw out moisture. The onion should be soft and jammy, not crisp.

Can the horseradish aioli be made without lemon juice?

Yes, the lemon juice adds brightness, but it can be omitted. The aioli will still be creamy and tangy from the horseradish and Dijon mustard. If you have white wine vinegar, you can use that instead in equal measure.

How do you keep the sandwiches from getting soggy?

Toasting the rolls until crisp is key. Also, do not over-saturate the beef in the jus—just a quick 30-second warm. When dipping, encourage each person to dip the sandwich right before eating rather than letting it sit in the jus. This keeps the bread crunchy.

Can this recipe be doubled for a party?

Absolutely. Double all ingredients and use a larger skillet or work in batches. Keep the assembled sandwiches warm in a low oven (200°F / 95°C) for up to 15 minutes before serving. Provide multiple bowls of hot jus for dipping so guests can dip without waiting.

Recipe card

French Dip Prime Rib Sandwiches with Swiss & Horseradish Aioli

Prep 15 minCook 20 minTotal 35 minServes 4

Ingredients

400 g thinly shaved prime rib or roast beef
4 crusty French rolls, split
8 slices Swiss cheese
1 large onion, caramelized
1/3 cup mayonnaise
1 tbsp prepared horseradish
1 tsp Dijon mustard
1 tsp lemon juice
2 cups rich beef consommé au jus

Instructions

In a small bowl, combine the mayonnaise, prepared horseradish, Dijon mustard, and lemon juice. Whisk until smooth and well blended. Set aside in the refrigerator while preparing the other components.
Pour the beef consommé into a large skillet and bring to a simmer over medium heat. Add the thinly shaved prime rib in a single layer and let it warm for 30 seconds, turning gently with tongs, until heated through and saturated with the broth. Let it rest for 3 minutes before slicing.
Preheat the broiler. Place the split French rolls cut-side up on a sheet pan and toast under the broiler for 1–2 minutes, until golden and crisp at the edges. Keep a close eye to prevent burning.
Spread a generous layer of the horseradish aioli onto the cut sides of each toasted roll. Pile the warm prime rib evenly onto the bottom halves, then top with the caramelized onions. Lay 2 slices of Swiss cheese over the top of each sandwich, covering the beef and onions completely.
Return the assembled sandwiches to the broiler and cook for 2–3 minutes, until the Swiss cheese is melted and bubbly with golden spots. Watch closely to avoid burning the bread.
Remove the sandwiches from the broiler and let them rest for 1 minute. Slice each sandwich in half diagonally with a serrated knife. Serve immediately with the remaining hot beef consommé on the side for dipping.

Contains: gluten, milk, eggs, mustard

Estimated nutrition per serving

Calories: 680
Protein: 38 g
Carbohydrates: 45 g
Fat: 38 g

Automatic estimate from the ingredient list, not laboratory-verified.

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This recipe is based on a short cooking video and is published under the pen name Clara Weller. It was checked before publication, but errors can slip through. Nutrition, when shown, is an estimate. Read more in our editorial policy and on our food safety page.