Thinly sliced roast beef, a toasted sesame bun and a little tangy sauce make a satisfying sandwich without needing a long list of toppings. This homemade version takes inspiration from that simple combination, using an oven-roasted joint of beef and an optional horseradish mayonnaise.
It is an Arby’s-inspired recipe, not the restaurant’s official recipe, and the flavour and texture will differ. A home-roasted joint and hand-cut slices will not be identical to commercially prepared sandwich meat.
There is no overnight marinade here. Instead, a measured seasoning rub keeps the preparation straightforward. The roast takes longer than a quick lunch to cook, but you can serve it freshly sliced or prepare it ahead using the storage instructions below.
Recipe at a Glance
- Makes: approximately 6 sandwiches
- Preparation time: approximately 20 minutes
- Estimated roasting time: 75–110 minutes
- Resting time: 15 minutes
- Assembly time: approximately 5 minutes
- Equipment: a roasting tin with a rack, food thermometer, carving board and sharp carving knife
Roasting time varies with the shape and starting temperature of the meat, as well as your oven. Use the thermometer reading rather than the clock to decide when the beef is ready.
Ingredients
For the Roast Beef
- 1 kg boneless beef top round, also called topside, preferably an evenly shaped roasting joint
- 1 tablespoon olive oil
- 1 teaspoon fine salt
- 1 teaspoon garlic powder
- 1 teaspoon onion powder
- ½ teaspoon ground black pepper
- ½ teaspoon sweet paprika, optional
For the Horseradish Mayonnaise
- 90 g mayonnaise
- 2 teaspoons prepared horseradish, drained if watery
- 1 teaspoon lemon juice
Use prepared grated horseradish rather than assuming that a ready-made creamy horseradish sauce will have the same strength. Start with the stated amount and adjust to taste.
To Assemble
- 6 sesame seed burger buns
- 15 g butter, softened, optional, for toasting the buns
Choosing the Beef
Top round or topside provides a lean joint that can be sliced across the grain for sandwiches. Choose one with reasonably even thickness so the narrow end does not cook much faster than the centre.
This method is written for an intact roasting joint. If your beef is mechanically tenderised, injected or supplied with specific cooking directions, follow the additional instructions on its packaging.
Lean beef benefits from thin slicing. Thick slices can feel chewy even when the meat has been cooked correctly.
How to Make the Sandwiches
1. Heat the oven and season the beef
Preheat the oven to 170°C conventional / 325°F. Place a rack inside a roasting tin.
Remove the beef from its packaging and pat dry with kitchen paper. There is no need to rinse it.
Mix the salt, garlic powder, onion powder, pepper and optional paprika. Rub the beef with olive oil, then distribute the seasoning over all sides.
Place the joint on the rack. Wash your hands and clean any surfaces or utensils that have touched the raw meat before preparing the sauce or buns.
2. Roast to the correct temperature
Roast uncovered, allowing approximately 75–110 minutes as a planning estimate. Begin checking the temperature after about 60 minutes, particularly if the joint is long and narrow.
Insert a food thermometer into the thickest part, avoiding large pockets of fat and contact with the rack. Check more than one position near the centre.
For an intact beef roast, the minimum internal temperature is 63°C / 145°F, followed by at least 3 minutes of resting. For this recipe, reach that temperature before removing the beef from the oven; do not rely on an assumed temperature increase during resting.
The colour of the centre is not a reliable safety check.
3. Rest the roast
Transfer the beef to a clean carving board with a groove to catch juices. Cover loosely with foil and rest for 15 minutes.
This exceeds the minimum three-minute rest and gives you time to prepare the sauce and warm the buns.
4. Mix the sauce
Stir the mayonnaise, prepared horseradish and lemon juice together in a small bowl.
Taste and add a little more horseradish if you prefer a stronger flavour. Keep the sauce covered in the refrigerator until needed.
This is a simple homemade horseradish mayonnaise, not a reproduction of the restaurant’s branded sauce.
5. Toast the buns
Split the buns. If using butter, spread a thin layer over the cut sides.
Toast cut-side down in a frying pan over a medium-low heat until lightly golden. Work in batches if needed and watch carefully to avoid burning.
6. Slice the beef thinly
Look for the direction of the muscle fibres and cut across the grain, using a sharp carving knife and a stable board.
Aim for thin slices, approximately 2–3 mm where practical. Do not worry if they are uneven. A sharp knife helps, but paper-thin deli-style slices generally require specialised equipment.
Remove any tough exterior connective tissue as you slice.
7. Assemble and serve
Spread a small amount of horseradish mayonnaise over the bottom half of each bun. Add approximately 100–120 g sliced cooked beef, depending on the roast’s final yield.
Fold the slices loosely rather than pressing them into a dense stack. Add the bun tops and serve promptly.
Helpful Adjustments
The beef seems chewy.
Check your slicing direction and cut thinner pieces. Slicing along the grain leaves longer muscle fibres, making each bite harder to chew.
The roast is browning too quickly.
Cover loosely with foil and continue cooking until the centre reaches the required temperature.
You prefer less pungent sauce.
Start with one teaspoon of horseradish, then taste before adding more. Plain mayonnaise is also an option.
You want extra toppings.
Sautéed onions or a slice of cheese can make a pleasant variation. Keep them optional so the roast beef remains the main ingredient.
Preparing the Beef Ahead
Chilled roast beef is often easier to slice neatly than warm beef, but allow time to cool and refrigerate it safely.
After resting, divide the roast into smaller portions if needed and place in shallow containers. Refrigerate within 2 hours of cooking, or within 1 hour if the surrounding temperature exceeds 32°C / 90°F. Do not leave the whole joint on the counter until it reaches room temperature.
Once chilled, slice across the grain. Store the beef separately from the buns and sauce so the bread does not become soggy.
Storage and Reheating
Keep cooked beef covered at 4°C / 40°F or below and use within 3–4 days. Prepare only as much sauce as you need, keep it refrigerated and follow any shorter storage instructions on its ingredients.
For warm sandwiches made with leftover beef, place the required slices in a saucepan with a small splash of beef stock or water. Cover and heat gently, turning the slices carefully, until they reach 74°C / 165°F throughout. Serve immediately; prolonged heating can dry out lean meat.
Reheating to this temperature may change the meat’s colour and texture compared with the freshly cooked roast.
For further information, see the safe minimum cooking temperature chart and the USDA’s guidance on leftovers and food safety.
A Final Thought from Adam
I appreciate recipes that explain the details a beginner might otherwise have to guess. With roast beef, knowing where to place the thermometer and how to slice across the grain is more useful to me than being promised a “perfect” result.
These sandwiches leave room for ordinary home cooking: slightly uneven slices, a familiar bun and a sauce adjusted to your taste. Give yourself enough time, follow the temperature checks and enjoy putting together a meal that feels manageable.
Recipe development note: This recipe was developed with AI assistance and has not been independently kitchen-tested for this article. Cooking times and yield are estimates.
Brand note: This is an independent, Arby’s-inspired recipe. It is not affiliated with or endorsed by Arby’s and does not reproduce its proprietary recipe.
