French Onion French Dip Sandwiches Recipe
These French Onion French Dip Sandwiches are everything you love about French onion soup and classic French dip sandwiches combined. With deeply caramelized onions, melty Swiss cheese, tender roast beef, and a savory beef broth for dipping, each bite is warm, gooey, and incredibly comforting.
Ingredients
- 2 large yellow onions thinly sliced
- 2 tbsp butter
- 1 tbsp olive oil
- 1 tsp sugar
- 1 tbsp balsamic vinegar
- 1 tsp fresh thyme leaves or ½ tsp dried thyme
- Salt and black pepper to taste
- 1 lb deli-style roast beef thinly sliced
- 4 French baguette rolls or 1 large baguette, cut into 4
- 4 –8 slices Swiss cheese
- ¼ cup mayonnaise
- 1 tbsp Dijon mustard
- 2 cups beef broth
- 2 cloves garlic minced
Instructions
- Start with the star of the dish, the onions! Melt butter and olive oil in a large skillet over medium-low heat. Add thinly sliced onions and cook them low and slow. Stir occasionally until they caramelize into a deep golden brown (about 30-40 minutes). Add in sugar, balsamic vinegar, fresh thyme, and a touch of salt and pepper. Cook another 5 minutes, allowing all the flavors to meld beautifully.
- Preheat your oven to 350°F (175°C). Slice the French baguettes in half lengthwise and place them on a baking sheet. Toast for about 5 minutes until crisp and golden. This step ensures the bread holds up to the juicy toppings!
- Spread mayonnaise and Dijon mustard on one side of each baguette. On the other side, add a slice of Swiss cheese. Next, pile on the thinly sliced roast beef generously. Finally, top it all with a spoonful of the caramelized onion mix for an added punch of flavor.
- While your sandwiches come together, heat the beef broth in a saucepan with minced garlic. Get it simmering hot, so it’s ready for dipping when you serve.
- Place each sandwich on a plate and pair it with a small bowl of the warm broth. Gather around, dip generously, and savor every flavorful bite.
Notes
- Be patient with the onions—low and slow cooking brings out their natural sweetness.
- Want extra melty cheese? Pop the sandwiches back in the oven after assembling for 1–2 minutes.
- Make it spicy: Add hot sauce or sliced jalapeños if you like some heat.