French Onion Roast Beef Sandwiches
These French Onion Roast Beef Sandwiches are everything you love about the classic soup—caramelized onions, savory broth, and melty Gruyere—packed into a warm, toasty baguette. It's cozy comfort food, perfect for a hearty lunch or casual dinner, and comes together in less than an hour.
Ingredients
- 1 long French baguette
- 1½ lbs 340g rare roast beef, thinly sliced
- 3 tbsp 42g unsalted butter
- 1 tsp fresh thyme leaves chopped
- 3 large yellow onions thinly sliced
- ½ tsp salt
- ½ tsp black pepper
- ¼ tsp red pepper flakes
- ½ cup 113ml cooking sherry
- 2 cups 454ml beef stock
- ½ tsp cornstarch
- 1 tsp water
- 10 oz Gruyere cheese grated
Instructions
- Slice baguette into 4 sections and cut each 3/4 through.
- Preheat oven to 500°F.
- Divide roast beef among sandwiches. Wrap in foil.
- Caramelize onions in butter and thyme for 20–25 mins.
- Add seasoning and sherry. Cook 3–4 mins.
- Add beef stock. Simmer 5 mins.
- See full steps with tips & photos → https://wimpysdiner.net/french-onion-roast-beef-sandwiches-2/
Notes
- Use a sturdy French baguette that can hold up to juicy fillings and dipping.
- Cooking sherry adds richness but can be substituted with white wine or omitted for non-alcoholic versions.
- Gruyere melts beautifully but you can also use Swiss or provolone.