Open Faced Roast Beef Sandwich
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Open-faced roast beef sandwiches are a tasty meal you can make at home. This recipe uses a slow cooker to make tender, flavorful beef that’s perfect for sandwiches. You’ll need a beef roast, some seasoning mixes, and beef broth. The meat cooks for 6-8 hours until it’s very soft.

To make the sandwiches, you’ll put mashed potatoes and the cooked beef on thick slices of toasted bread. Then you’ll add some of the cooking liquid and sprinkle cheese on top. It’s a filling meal that’s great for dinner or lunch.

Exact Ingredients List
Here’s what you’ll need to make these tasty open-faced roast beef sandwiches:
- 5 pounds beef roast (chuck or rump)
- 4 ounces au jus seasoning mix (2 packages)
- 4 ounces dry Italian salad dressing mix (2 packages)
- 32 ounces low-sodium beef broth
- 4 cups mashed potatoes
- 8 slices thick, crusty bread (like Texas Toast)
- 1/2 cup freshly shredded gruyere cheese
You’ll also want to have cooking spray on hand for your crockpot.
The beef roast is the star of this dish. Pick a good quality chuck or rump roast for the best flavor and texture.
The seasoning mixes add lots of flavor to the meat as it cooks. Look for au jus and Italian dressing mixes in the spice aisle of your grocery store.
For the bread, choose a thick, hearty variety that can stand up to the toppings. Texas Toast works great, but any crusty bread will do.
Don’t forget the gruyere cheese! Its nutty flavor pairs perfectly with the savory beef.
Instructions
Cook the Beef: Spray your crockpot with nonstick spray. Place a 5 pound beef roast inside and sprinkle with 4 ounces each of au jus seasoning and dry Italian salad dressing mix. Pour 32 ounces of beef broth over the roast, and cook on high for 6-8 hours or until tender.

Shred the Beef: When cooked, strain the broth into a bowl and reserve. Shred or slice the beef into small bite-sized sections. Discard away any fat and gristle.

Assemble the Sandwiches: Prepare 4 cups of mashed potatoes. Toast 8 slices of bread. For extra-thick slices, broil for 2-4 minutes until golden. Assemble the open-faced sandwiches by placing the toasted bread on a plate and topping it with mashed potatoes. Add a generous portion of the shredded/sliced beef. Drizzle a couple of spoonfuls of the reserved au jus over the meat and sprinkle with ½ cup of freshly shredded gruyere cheese. Serve with a knife and fork. Enjoy!

Possible Substitutes List & Recipe Variations
You can swap out ingredients to make this open-faced roast beef sandwich your own. Try using pork roast or turkey instead of beef. For the bread, sourdough or rye make tasty alternatives to Texas toast.
Don’t have gruyere? Swiss or provolone cheese work well too. If you’re not a fan of mashed potatoes, try roasted or fried potatoes as a base.
For a lighter version, use lettuce wraps instead of bread. You can also add veggies like sautéed mushrooms or caramelized onions for extra flavor.
Here are some quick substitutions:
- Meat: Pork, turkey, chicken
- Bread: Sourdough, rye, ciabatta
- Cheese: Swiss, provolone, cheddar
- Potatoes: Roasted, fried, sweet potato mash
Want to spice things up? Add horseradish sauce or Dijon mustard to the sandwich. For a crunchy texture, top with crispy fried onions.
Remember, you can adjust the cooking time if using a different type of meat. Always make sure it’s cooked to a safe temperature before serving.
Tips, Tricks & Storing
To make your roast beef extra tender, cook it on low for 10-12 hours instead of high for 6-8 hours. This slow cooking method allows the meat to become fall-apart soft.
For maximum flavor, sear the roast on all sides in a hot pan before adding it to the crockpot. This step creates a tasty crust and locks in the juices.
Try different cheese options like cheddar, Swiss, or provolone to change up the flavor profile. You can also add caramelized onions or sautéed mushrooms for extra zest.
Store leftover beef and au jus separately in airtight containers in the fridge for up to 3 days. Reheat the beef in the microwave or oven, and warm the au jus on the stovetop.
Freeze extra beef for later use. Wrap it tightly in plastic wrap and foil, then place in a freezer bag. It will keep for up to 3 months. Thaw in the fridge overnight before reheating.
To prevent soggy bread, toast it right before serving. You can also brush the bread with olive oil and broil it for a crispy texture.