Do you know what is absolutely perfect? A roast beef sandwich. Seriously. They are one of my favorite foods and when they’re made right? Heaven. It took a while for me to figure out an exact process that created a sandwich that was flavorful and tender without being overkill. That is until I tasted this open faced roast beef sandwich recipe. It creates a beef that rivals any other than I’ve ever tasted and when you add cheddar and veggies? It’s a meal on a bun! It is seriously one of my favorite recipes period now! It has taken a backseat to my homemade chicken and noodle soup lately because of the cold, but it’s a close second! We’ve had it for lunch at least once a week for the last week, but it makes a fantastic dinner idea too!

The key to making the beef in this sandwich recipe so tender is marinating it. You can cook the beef in as little as 30 minutes of soaking but honestly? I recommend that you marinate it for 3-4 hours before doing so. The longer you let the beef marinate, the more tender and flavorful it will be. I find it is easiest to marinate the beef in a Ziploc bag, but it’s up to you what you use. You’re going to end up with a fantastic roast beef and cheddar sandwich no matter what you use to marinate it in. I just like that I can dump everything into the baggie, seal and go. When you’re cooking the roast beef, cook it to your tastes. I prefer mine well done, but Tom and Emma both prefer medium rare. Cooking it to your preferences won’t change the taste (or the awesomeness) of your sandwich.
Open Faced Roast Beef and Cheddar Sandwich Recipe
When you look at the cost of this sandwich, it honestly can be made an expensive or a budget friendly recipe. I pick up the steak needed to make the roast beef flavor on clearance whenever I can and use my Foodsaver to vacuum seal it. The steak used is pretty cheap anyhow but clearance is even cheaper. If you’re looking to up the quality (and the cost with it), simply use a more expensive cut of beef. It is the marinade that gives it the majority of its flavor so changing the cut won’t hurt much.
This recipe uses shredded cheddar. You can use the bagged stuff, but if you really want to kick up the flavor? Shred the cheese yourself. Freshly shredded cheese is so much more flavorful than the bagged stuff. Not to mention its cheaper too!

You Will Need:
- 5 oz. Flank Steak
- 2 oz. Cheddar cheese, shredded
- 1/8th Avocado, mashed
- 1 slice French bread
- 5 – 6 Fresh Spinach leaves (or more if you prefer)
Roast Beef Marinade Recipe:
- 2 tbsp. Olive Oil
- 1 tsp Balsamic Vinegar
- 1 tsp Worcestershire Sauce
- ½ tsp Dijon mustard
- 1/8 tsp Garlic powder
- Salt and pepper as desired

Make your beef marinade first by combining the olive oil, balsamic vinegar, Worcestershire sauce, and garlic powder. Stir well to combine then season with salt and pepper to your preferences.

Using a meat mallet, tenderize and pound your flank steak thin. Then, cut into strips 1-2″ strips and place inside of a Ziploc bag. Pour the marinade mix over the meat then close the bag. Shake well to coat the meat and refrigerate until you’re ready to cook it.

When you’re ready to cook your sandwich, use an avocado tool to scoop and mash the avocado. Then in a heavy bottom medium skillet, saute the beef slices until they are done to your liking.

Toast the bread the lightly butter one side. Spread the mashed avocado onto the buttered side then lay the spinach leaves down on top of the avocado. Add your cooked steak to the bread.

Place the entire sandwich on a broiler pan then spread the shredded cheddar evenly onto the steak. Broil for 1-2 minutes or until your cheese is fully melted.

Once the cheese is melted, remove your sandwich from the broiler and garnish with tomatoes! You can add any other sandwich toppings you want at this point, but trust me. It doesn’t need it! The meat is so flavorful that adding any other condiments could very easy ruin the taste of the entire thing. Serve up and enjoy because I am 100% positive that you will!
Open Faced Roast Beef Sandwich

Serve up a delicious sandwich with very little work! This open faced roast beef and cheddar sandwich recipe is the best you’ll ever taste! It’s amazing!
- 5 oz. Flank Steak
- 2 oz. Cheddar cheese (shredded)
- 1/8 th Avocado (mashed)
- 1 slice French bread (or any sort of bread you prefer)
- 5 – 6 Spinach leaves (or more if you prefer)
- Marinade for Beef:
- 2 tbsp. Olive Oil
- 1 tsp Balsamic Vinegar
- 1 tsp Worcestershire Sauce
- ½ tsp Dijon mustard
- 1/8 tsp Garlic powder
- salt and pepper as desired
- Mix up the marinade and marinate the beef for a minimum of ½ hour, to 4 hours.
- In a fry pan on med-high, quickly sauté the beef to your liking (well done, medium, medium rare, etc.) and set aside.
- Toast the bread
- Assemble the sandwich as follows: lightly butter the toasted bread and then spread the mashed avocado over the entire surface. Lay down the spinach leaves on top of the avocado and then lay the beef on top of that.
- Sprinkle the cheese on top of the beef and broil for 1 – 2 minutes or until the cheese is melted
- Garnish with a few slices of tomato.