French Dip Grilled Cheese with Caramelized Onions and Rich Au Jus Recipe

Ingredients

• 8 slices, about 2.5 cm thickcrusty French bread
• 8 slices, at room temperatureSwiss cheese
• 340 g (12 oz)thinly sliced deli roast beef
• 2 medium, thinly sliced about 3 mm thickyellow onions
• 85 g (6 tablespoons), dividedunsalted butter
• 15 ml (1 tablespoon)olive oil
• 480 ml (2 cups)low-sodium beef broth
• 10 ml (2 teaspoons)Worcestershire sauce
• 5 ml (1 teaspoon)soy sauce
• 1 clove, mincedgarlic
• 1 sprigfresh thyme
• to tastesalt
• to tasteblack pepper

Instructions

1. 1

   Caramelise onions

   Take the Swiss cheese out of the fridge and leave it at room temperature for 15–20 minutes. Heat 1 tablespoon of the butter with the olive oil in a large frying pan over medium heat. Add the onions and cook, stirring frequently, for 12–15 minutes, until deeply golden and caramelised. Transfer them to a plate.

2. 2

   Make the au jus

   While the onions cook, combine the beef broth, Worcestershire sauce, soy sauce, minced garlic and thyme in a small saucepan. Bring to a gentle simmer and cook for 5 minutes. Season with salt and pepper to taste, then strain through a fine-mesh sieve. Keep warm over the lowest heat until serving.

3. 3

   Assemble sandwiches

   Lay 4 slices of bread on a work surface. Top each with 1 slice of Swiss cheese, about 3 ounces of roast beef folded to cover the bread, some caramelised onions and another slice of cheese. Add the remaining bread slices and press gently. Spread about ½ tablespoon of softened butter over the top of each sandwich, then carefully turn them over and butter the other side.

4. 4

   Grill the sandwiches

   Heat a clean frying pan or griddle over medium heat. Put the sandwiches in butter-side down and cook for 3–4 minutes, pressing gently with a spatula, until deeply golden with visible grill marks. Flip and cook for another 3–4 minutes, until the cheese has melted. If it is melting too slowly, lower the heat to medium-low and cover the pan for the final minute.

5. 5

   Rest and serve

   Take the sandwiches off the heat and leave them to rest for 1 minute. Slice diagonally and serve straight away with small bowls of warm au jus for dipping.

What is a French dip grilled cheese?

The French dip is an American sandwich traditionally served with beef juices or broth for dipping; despite its name, it is not a French dish. This version brings those savoury flavours into grilled cheese, layering roast beef, Swiss cheese and onions between slices of crusty bread.

The combination works because the cheese melts around the beef while the onions add sweetness, and the au jus brings extra savoury depth to each bite.

Nutrition and macros by portion

The nutrition label shows one serving as written: 720 calories, 39g protein, 52g carbs, 38g fat.

Bread supplies most of the carbohydrates, while butter and cheese contribute much of the fat; roast beef and Swiss cheese provide most of the protein. Balance the plate with a green salad or vegetables, and use the au jus as a dip rather than pouring it over the sandwich.

Give the onions time

Even slices: cutting the onions to a similar thickness helps them soften and brown at roughly the same pace.

Steady heat: cook them over medium heat, stirring often, for the full 12–15 minutes. They should be deeply golden and soft, not merely translucent.

Build a balanced sandwich

Layer order: placing cheese on both sides of the roast beef helps hold the filling together as it melts. Fold the beef over the bread for more even coverage.

Bread choice: crusty French bread gives the sandwich structure and a crisp exterior. Slices about 2.5 cm thick can hold the filling without becoming too fragile.

Keep the au jus savoury

Gentle simmer: the broth, Worcestershire sauce, soy sauce, garlic and thyme need only 5 minutes together to make a flavourful dip. Avoid a vigorous boil.

Season last: strain the sauce before adjusting the salt and pepper, since the broth and sauces already contribute savouriness. Keep it warm on the lowest heat until the sandwiches are ready.

Get the cheese melted

Golden outside: cook over medium heat for 3–4 minutes per side, pressing lightly rather than flattening the sandwich. The bread should brown while the cheese softens inside.

If the bread is colouring before the cheese melts, turn the heat down to medium-low and cover the pan for the final minute, as directed.

Serve it hot

Rest the sandwiches for 1 minute before slicing so the melted filling settles slightly. Serve while the bread is still crisp, with warm au jus alongside for dipping.

A simple green salad or steamed green vegetables make a fresh counterpoint to the rich sandwich.

Recipe notes & tips

• Let the cheese come to room temperature for 15–20 minutes so it is ready to melt.
• Stir the onions frequently so they colour evenly during their 12–15 minutes in the pan.
• Fold the roast beef rather than laying it flat to distribute it more evenly across each sandwich.
• Keep the au jus warm over very low heat while you grill the sandwiches.
• Use a spatula to press gently; pressing too hard can squeeze out the filling.
• Serve the au jus in small bowls so each person can dip without softening the whole sandwich.

Variations

• Add mushrooms: sauté sliced mushrooms with the onions for an earthier filling.
• Try another cheese: use provolone in place of Swiss for a milder, stretchy melt.
• Use leftover beef: thinly slice cooked roast beef and warm it briefly before assembling.
• Add fresh herbs: finish the onions with a little chopped parsley for a fresh note.
• Make it sharper: add a small spoonful of Dijon mustard inside each sandwich.

Common mistakes to avoid

• Rushing the onions: pale onions lack the recipe’s caramelised sweetness; give them the full 12–15 minutes.
• Using high heat: the bread can brown before the cheese melts; lower the heat and cover for the final minute if needed.
• Overfilling the bread: too much beef or onion makes flipping difficult; spread the filling evenly and keep it within the slices.
• Skipping the cheese on one side: the filling is less cohesive; use a slice of Swiss above and below the beef.
• Boiling the au jus hard: a vigorous boil is unnecessary; bring it to a gentle simmer for 5 minutes.
• Serving the dip cold: keep it warm on the lowest heat until the sandwiches are ready.

How to store

Store leftover sandwiches and au jus separately in airtight containers in the fridge for up to 3 days. Reheat the sandwiches in a frying pan over medium-low heat until hot and crisp, and warm the au jus gently in a saucepan.

Frequently asked questions