Leftover Pot Roast French Dip Sandwich with Au Jus
Transform leftover pot roast into restaurant-style French dip sandwiches with caramelized onions and melted Swiss cheese. The reserved cooking liquid becomes a rich au jus for dipping, while a simple vinaigrette-dressed salad provides fresh contrast. This comforting meal maximizes Monday's pot roast, creating an entirely new dining experience that feels special rather than like leftovers.
Ingredients
- 1 onions, medium, thinly sliced
- 1 baguettesmall French-style rolls1 per servingcomfort
Use individual rolls instead of slicing baguette
Full guide → - 2 Tbsp butter
- 2 Tbsp butter
- 4 cups pot roast, leftover, chopped
- 4 slices cheese, Swiss
- 1 cup reserved pot roast cooking liquid, leftover
- 1 Tbsp soy sauce, low-sodium
- 1 tsp cornstarch
- 1 Tbsp vinegar, white wine
- 2 tsp mustard, Dijon
- ½ tsp honey
- 2 ½ Tbsp oil, olive
- 6 oz mixed greensany salad greens1:1fresh
Any lettuce or salad mix works
Instructions
- 1
Turn on oven broiler and place rack 6 inches beneath heat source
- 2
Melt first portion of butter in skillet over medium heat
- 3
Add onions with salt to melted butter and saute until translucent and tender
- 4
Add leftover pot roast and saute until heated through
- 5
Set meat and onions aside and return pan to heat
- 6
Add cooking liquid to heated pan, scraping up browned bits
- 7
Whisk together soy sauce and cornstarch
- 8
Whisk soy sauce mixture into simmering liquid and cook for 1 minute
- 9
Pour au jus into small bowls for serving
- 10
Place baguette cut-side up on sheet pan
- 11
Spread with second portion of butter and toast until lightly golden
- 12
Fill sandwiches with meat mixture and top with Swiss cheese
- 13
Broil until cheese is melted
- 14
Toss greens with vinaigrette just before serving
- 15
Serve sandwich with au jus for dipping and salad on side
Tips
Use large grain mustard if available for extra texture in the vinaigrette
Make sure onions are very tender before adding pot roast for best flavor
Keep au jus warm while assembling sandwiches for optimal dipping
Good to Know
Assembled sandwiches best eaten immediately. Store components separately in refrigerator for up to 3 days.
Caramelize onions and make au jus up to 2 days ahead. Reheat gently before assembling.
Serve immediately while cheese is melted and bread is toasted.
Common Mistakes
Don't skip scraping browned bits when making au jus to avoid losing flavor
Avoid over-toasting bread initially since it goes back under broiler with cheese
Substitutions
Use individual rolls instead of slicing baguette
Full guide →Any lettuce or salad mix works
FAQ
Can I use different cheese instead of Swiss?
Yes, provolone, Gruyere, or mild cheddar work well. Choose melting cheeses that complement beef.
What if I don't have reserved cooking liquid?
Use beef broth with a splash of red wine and season with salt and pepper for similar flavor.
How long will leftover sandwiches keep?
Best eaten fresh, but components can be stored separately for 3 days and reassembled when needed.