Broiled garlic toast topped with tender roast beef and tangy horseradish makes this the fastest way to turn leftovers into a craveable, steakhouse-style open faced roast beef sandwich. It’s ready in under 20 minutes and perfect for an easy weeknight dinner.
Why This Sandwich Works
Flavor: Rich, savory beef meets buttery crunch with a bold, zippy kick and just enough sweetness to balance every bite.
Technique: Use the broiler in this beginner-level recipe to quickly crisp the bread and create a sturdy base under the toppings.
Budget: This budget friendly roast beef baguette sandwich is this a great way to stretch leftovers or you can use deli roast beef when needed.
Serving Suggestions: I like to serve these open-faced so they are quick and easy to grab. Or add a second slice of toast to make a full sandwich when we’re extra hungry. They’re also one of my go-to “set it out and build” party platters, perfect for game day or casual hosting.
Flavor-Packed Ingredients
Baguette: Choose a sturdy, crusty loaf similar to a baguette, so it stays crisp under the spreads, or swap in ciabatta, sourdough, or another thick-cut rustic style bread.
Beef: This is best made with leftovers or a home-cooked roast, but deli roast beef works in a pinch.
Butter: Softened butter spreads evenly for full-to-edge browning, or swap in mayo if you want extra crisping under the broiler.
Optional Toppings: Add onion or garlic jam (or swap in fig jam, pepper jelly, or bacon jam) for sweet and savory contrast, mild or extra-hot horseradish sauce for a bit of zing, and Dijon or stone-ground mustard for a sharp flavor.
How to Make a Roast Beef Sandwich
Cut a baguette into 6 pieces (full recipe below).
Butter each piece of bread, sprinkle on garlic powder and chopped parsley.
Broil until the tops are browned.
To each piece, add horseradish and Dijon mustard to taste.
Top with slices of roast beef and serve with au jus or dipping sauce of your choice.
Little Tricks that Help
Broilers vary, so keep the tray close and watch carefully to prevent scorched edges.
For more tender meat, warm beef briefly in a covered skillet with a splash of broth.
Keep spreads off the very edges of the toast so the crust stays crisp and is easy to pick up.
Make a “one-bowl sauce” by mixing horseradish sauce and Dijon, then use onion jam as the sweet layer.
Add some melty cheese by adding provolone or Swiss on the toast for the last 30 to 60 seconds under the broiler.
Best Leftovers
Place leftover roast beef in an airtight container and refrigerate for up to 4 days, or freeze for up to 3 months. Thaw roast beef before using.
It is best to store sandwich ingredients separately so the bread does not become soggy. But if some have been assembled, cover and refrigerate for a day, then re-crisp the sandwich under the broiler for 30 to 90 seconds.
Preheat the oven to broil. Line a baking tray with foil paper.
Cut half of a baguette lengthwise to expose the bread, cut each half into thirds. You’ll have 6 open faced pieces.
Spread 1 Tablespoon of butter on each piece of bread and place on foil lined baking tray. Sprinkle each piece with garlic powder and parsley to taste.
Broil until browned, about 2-3 minutes.
To each piece, add 1 Tablespoon of onion jam (or to taste), 1 Tablespoon of horseradish (or to taste), and 2 teaspoons mustard (or to taste). Add a couple of slices of roast beef and serve.
Notes
Nutrition calculated without onion jam.
Leftover roast beef will keep for 4 days in the refrigerator, or freeze for up to 3 months. Thaw before using.
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Nutrition information does not include optional ingredients or garnish and is an estimate. It may change based on actual ingredients and cooking methods used.
I am a wife, mother of two, and professional accountant. I love fantastic food, and it is so often the center of our lives, from everyday dinner, to family gatherings, and special evenings at fabulous restaurants. I have always loved cooking and baking, with my mom and grandma, and now, with my daughter and son. I love trying new recipes while enjoying my favorites too. I’m so happy to share them with you. See more posts by Candace
