French Onion Beef Dip Sandwiches

French onion beef dip sandwiches
Prep Time
15 min
Cook Time
1h 40 min
4-6 servings

Consider this a mash-up of two comfort food classics — French onion soup and a beef dip sandwich. With the right treatment, an affordable sirloin tip gets transformed into a juicy, tender cut that is the perfect pair for caramelized onions, melted gruyere cheese and a luxe French onion jus. Make sure not to skip the horseradish mayo, it offers some much-needed brightness to cut through all the richness.

Related: Herb and Goat Cheese Sheet Pan Frittata Sandwiches



French Onion Jus

Tbsp olive oil
cup unsalted butter
large sweet or yellow onions, thinly sliced lengthwise
Salt, to taste
Pepper, to taste
cup cooking sherry or dry red wine
cups beef stock
beef bouillon cubes
Tbsp Worcestershire
thyme sprigs
Tbsp sherry vinegar

Roast Beef

lb sirloin tip roast
cup unsalted butter
Tbsp chopped rosemary
Tbsp chopped thyme leaves
cloves garlic, minced
tsp kosher salt
tsp pepper
medium onion, sliced into ½-inch rings
Kosher salt, to taste
Pepper, to taste

Horseradish-Mayo Spread

cup mayonnaise
Tbsp prepared horseradish (adjust based on strength of horseradish)
Tbsp chopped chives, optional
tsp grainy Dijon mustard
tsp lemon juice
tsp kosher salt

Sandwich assembly

White sandwich rolls, such as ciabatta or Portuguese rolls
Sliced gruyere or provolone cheese


Ingredients for French onion beef dip sandwiches
Step 1

Remove beef from fridge and bring to room temperature for 1 hour.

Step 2

To make the French onion jus, heat oil and butter in a large pot over medium heat. Add sliced onions, season with salt and pepper and cook, stirring frequently, until onions reduce in volume by about ⅓ and begin to soften, 8 minutes.

Cooked onions in a Dutch oven
Step 3

Reduce heat to low and cook, stirring occasionally, until onions are deep brown and jammy, 1 – 1 ½ hours. If onions begin to stick to the bottom of the pot or seem at risk of burning, add a few tablespoons of water and scrape up any brown bits and continue cooking. Add sherry or wine and cook until liquid is mostly evaporated, about 3 minutes. Remove about half of the caramelized onions from the pot and reserve for later.

Caramelized onions in Dutch oven
Step 4

Slowly pour in beef broth and stir in Worcestershire, beef bouillon cubes and thyme sprigs. Bring to a boil, reduce heat to low and simmer until thickened slightly, 30 minutes. Remove thyme sprigs and stir in sherry vinegar. Taste, and season with more salt, if needed.

Broth added to Dutch oven
Step 5

Meanwhile, prepare the roast beef. Preheat oven to 450°F. In a small food processor or blender, add the butter, chopped herbs, garlic, salt and pepper. Blitz together until well combined and smooth. Pat the meat dry with paper towels and arrange on top of onion slices in a medium baking dish.

Beef placed on top of onions in baking dish
Step 6

Spread butter mixture all over the meat to evenly coat. Sprinkle generously with salt and pepper all over.

Beef coated with butter
Step 7

Transfer beef to the middle rack of the oven and roast at 450°F for 15 minutes. Reduce heat to 300°F, and continue to roast until cooked through and the internal temperature of the thickest part of the meat registers 130°F-140°F for medium-rare, 15-20 minutes per pound. The meat will continue to cook once removed from the oven, so aim for a few degrees below the target temperature. Allow to rest for at least 20 minutes before slicing. Roast beef can be made a day ahead.

Step 8

To make the horseradish-mayo spread, stir together mayonnaise, horseradish, chives, mustard, lemon juice, and salt in a medium bowl to combine.

Horseradish-mayo spread in a bowl
Step 9

Slice roast beef with a sharp knife into very thin slices, working against the grain of the meat.

Step 10

Slice each bun in half lengthwise and arrange on a large baking sheet (you may need to work in batches). Spread both pieces of bread with horseradish mayonnaise spread. Divide meat and caramelized onions among buns and top with thin slices of gruyere.

Open sandwiches on a baking sheet
Step 11

Transfer to oven and broil until cheese is just melted and buns are lightly toasted, 3-5 minutes.

Sandwiches toasted and topped with melted gruyere
Step 12

Serve sandwiches with a side of French onion jus for dipping.

Sandwich being dipped in onion jus

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