Slow-Cooked Arby's Inspired Roast Beef Sandwiches on Onion Rolls

Slow-cooker roast beef cooked for slicing, dunked in rich jus, and stacked on toasted onion rolls for a copycat arby roast beef sandwich at home.

Prep Time 25

Cook Time 5 35

Total Time 6

Course Main Dish

Cuisine American

Servings 6

6-quart slow cooker a 6 quart crock pot is ideal so the roast sits snugly; a Dutch oven in a low oven works too, but you'll need to watch the liquid level
Instant-read thermometer helps you nail sliceable doneness (think roast beef, not shreddable pot roast); if you skip it, use a thin knife to check tenderness and keep the cook gentle
large rimmed sheet pan or casserole dish for chilling the cooked roast so it firms up for thin slicing; a loaf pan also works in a pinch
Sharp slicing knife a long carving knife is best; an electric knife is great; a deli slicer makes it ultra-thin but is not required
Fine mesh strainer for a cleaner jus; you can also ladle carefully and leave sediment behind
Small saucepan only needed if you're making the optional cheddar sauce; microwave works, but stovetop gives smoother control

3 pound top sirloin roast or use beef arm roast for a beefier pot-roast-style flavor; avoid heavily marbled chuck if you want deli-like slices
2 teaspoon kosher salt if using fine salt, reduce slightly
1 1/2 teaspoon garlic powder granulated garlic also works
1 1/2 teaspoon onion powder this is part of the classic fast-food roast beef vibe
1 teaspoon paprika sweet paprika for color; smoked paprika is fine if you like a little campfire note
1/2 teaspoon black pepper freshly ground if possible
2 cup low-sodium beef broth or use stock; you can add more later if you want extra dipping jus
1 cup water keeps the jus from getting too salty as it reduces and concentrates
1 tablespoon worcestershire sauce adds that savory depth that makes the broth taste like more than broth
1 tablespoon soy sauce optional, but it gives a deli-style umami boost; use tamari if gluten-free
1 yellow onion sliced into thick rounds to flavor the jus; it's not meant to be the star

6 onion roll store-bought is perfect; brioche bun works if you cannot find onion rolls
2 tablespoon unsalted butter for toasting; swap with mayo for extra browning if you like
1/2 cup prepared horseradish drained; mix into mayo for a quick sauce, or serve plain
1/2 cup mayonnaise or use sour cream for a tangier spread

2 tablespoon unsalted butter salted is fine, just taste before adding more salt
2 tablespoon all-purpose flour this thickens the sauce; for gluten-free, use cornstarch slurry instead
1 cup whole milk 2% works; half-and-half makes it richer
6 ounce sharp cheddar cheese shredded; pre-shredded works but melts smoother if you shred it yourself
1/4 teaspoon garlic powder optional
1/4 teaspoon kosher salt taste and adjust depending on your cheese

Pat the roast dry with paper towels (dry surface = better flavor). In a small bowl, mix salt, garlic powder, onion powder, paprika, and black pepper. Rub the seasoning all over the top sirloin roast, pressing so it adheres.
Scatter the sliced onion in the bottom of a 6 quart slow cooker. Pour in beef broth, water, worcestershire sauce, and (if using) soy sauce. Set the seasoned roast on top of the onions. The liquid should come partway up the sides, not fully submerge the meat.

Cover and cook on low for 330 minutes. You are aiming for roast beef you can slice thin, so check doneness with an instant-read thermometer. For a tender, sliceable result, target about 135-145F in the thickest part. If you prefer more well-done (still sliceable), go to 150F, but stop before it turns into pull-apart pot roast.
Transfer the roast to a rimmed sheet pan or casserole dish. Tent loosely with foil and let it cool for 15 minutes so the juices settle.

Strain the cooking liquid into a bowl or measuring pitcher (discard onion slices or save them for another use). Skim excess fat if desired. Taste the jus and adjust: if it tastes flat, add a small splash of worcestershire; if it is too strong, dilute with a little water.
This is the not-so-secret secret for a homemade arby's roast beef sandwich texture: chill the roast. Refrigerate the roast on the sheet pan until it is firm enough to slice very thin, about 45 minutes. If you are making ahead, cover and chill overnight.

Warm the strained jus in a saucepan over medium heat until steaming but not boiling. While it warms, slice the chilled roast as thinly as you can across the grain. If you have a deli slicer, this is the moment to show off; otherwise, use a long sharp knife and take your time.
Add the sliced beef to the hot jus in batches and let it heat through for about 2 minutes per batch. This dunk-and-warm step gives you that classic juicy deli roast beef vibe even if your slices are not paper thin.
Split the onion rolls. Spread a thin layer of butter on the cut sides and toast in a skillet over medium heat until golden, about 3 minutes.
Stir together mayonnaise and prepared horseradish for a quick horseradish mayo (or serve them separately if you like to control the heat). Spread on the toasted rolls. Pile on a generous mound of the hot, jus-soaked beef and serve with extra warm jus on the side for dipping.

In a small saucepan over medium heat, melt butter. Whisk in flour and cook for 1 minute to remove the raw flour taste. Slowly whisk in milk until smooth and slightly thickened, about 3 minutes.
Reduce heat to low. Add cheddar a handful at a time, whisking until melted and smooth. Season with garlic powder and salt. Drizzle over the beef before closing the sandwiches if you want a beef-and-cheddar style finish.