With a creamy mayo-steak sauce spread, grilled onions, and two kinds of cheese, you’ll love these leftovers!

Why You’ll Love This Recipe
I don’t know about you, but when I make a roast, I almost always have leftovers. Well, these Leftover Pot Roast Patty Melts are the best thing to happen to leftover roast since….EVER!
In fact, I purposely cook extra roast now, just to make sure I have enough leftovers to make these sandwiches the next day.
With a creamy mayo-steak sauce spread, caramelized onions, and two kinds of cheese, these sandwiches are the best variation on a patty melt I’ve ever tried.
The grilled onions are the star of these sandwiches, as far as I’m concerned. Sure, it takes a little bit of time and attention to get them caramelized just right. But it’s SO worth it!
Believe me when I say that this sandwich is the epitome of diner-style comfort food. I highly recommend some French fries or homemade potato chips on the side.

These hearty, satisfying meal was also huge hit with my husband and hungry boys! And none of them like onions–or so they tell me.
Sliced sourdough is my favorite bread for making these sandwiches, but it’s leftovers, so use whatever you have on hand.
And don’t skip the sauce! It’s just mayonnaise and steak sauce, so it’s super easy, but it’s the perfect accompaniment to these beefy sandwiches.
You can grill these on a stove-top or electric griddle, or in a panini press or George Foreman style grill. No matter how you cook them up, you’re going to love these leftovers!
Next time you make a roast for dinner, make sure you’ll have enough meat left for these amazing Leftover Pot Roast Patty Melts. You won’t regret it!
Be sure to save this recipe to your favorite Pinterest board for later.

Ingredients
- Leftover pot roast
- Bread
- Butter
- Onions
- Salt and pepper
- Provolone cheese
- Cheddar cheese
Leftover Pot Roast Patty Melts
Ingredients
For the sandwiches:
- 2-3 cups leftover shredded pot roast
- 8 slices sturdy bread
- 3 tablespoons butter plus more for the bread
- 2 medium onions thinly sliced
- Salt and pepper to taste
- 4 slices Provolone cheese
- 4 slices cheddar cheese
For the sauce:
- 1/2 cup mayonnaise
- 3 tablespoons steak sauce
- 1/8 teaspoon pepper
Instructions
- Re-heat the pot roast in the microwave. Butter one side of all 8 slices of bread.
- Melt 3 tablespoons of butter in a large skillet. Add onions and cook over medium heat, stirring frequently, until onions are soft and golden brown.
- Season with salt and pepper and remove from heat.
- Combine the sauce ingredients in a medium bowl.
- Heat a griddle over medium-high heat. Spread a layer of the sauce on the unbuttered side of 4 slices of bread. Top with a piece of cheddar cheese.
- Top each slice of cheddar with about 1/2 cup of pot roast, a generous portion of onions, and the slice of Provolone cheese. Top with the remaining slice of bread, buttered side out.
- Grill, flipping once, until both sides are browned and crispy.
- Serve patty melts with the remaining sauce, for dipping.
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20 comments
margie
These were perfect! We used a sturdy bread, but could only eat half a sandwich each. Means I have lunch for next week! Thanks for such a creative and delicious recipe. Easy too!
Elizabeth Bull
What is a good bread?
Sharon
I have the same question. What is “sturdy” bread?
Danelle
Like a crusty sourdough type bread. Not just regular sandwich bread.
Monica Booth
This recipe was a hit! It seriously tasted like something I’d order in a higher-end pub-style restaurant. I accidentally crisped the onions up a bit in the frying pan but they ended up adding a nice hint of crunch. I could put that sauce on a flip flop and eat it happily. I’d never thought to mix mayo and bbq sauce together! If I do anything different next time, it’ll be to get a bigger loaf of bread lol. So good I’m making it again for lunch tomorrow!