May 9, 2018
updated
All the articles & recipes on this website have been created through real-life testing and experience (no ai) since 2010. This post may contain affiliate links. Please read our disclosure policy.
This lunch tastes and looks, gourmet, because it’s that good. However, this Philly Grilled Cheese Sandwich is made with none other than leftovers. Keep scrolling; it gets better.

No doubt, you’re probably always wondering what to do with that small serving of beef from steak night, fajitas, or a slow cooker stew, I know I am!
Most of the time, these leftovers are just enough for one person to enjoy the same meal twice; and since you most likely have more than one person to feed, you’ve got to stretch those leftovers.
With the help of my kids and my husband’s love for the classic Philly Cheesesteak Sandwich, I found the best way to use that leftover beef is by turning it into a Grilled Philly Sandwich!
It’s a meal that both kids and adults will love. The veggies and steak layered between melted cheese… C’mon what’s not to love?
And you’ll find more epic lunch ideas to love in my latest ebook:
101 Packed Lunches eBook
All my best kid-friendly lunches from over a decade of creating meal plans. Add some variety to your child’s lunchbox with these epic lunches, plus receive my Pack Meals Like a Pro ebook, free with purchase!
Of course, if leftovers steak is unheard of in your home, this could also be made with deli-sliced roast beef. I promise it’s a total upgrade from a regular sandwich.
But how does one pack a grilled sandwich inside a lunchbox you ask? Simple! Check out this easy and quick video.
This makes one incredibly EASY dinner idea or an EPIC lunch that both kids and adults will love.
Philly Grilled Cheese Sandwich Lunch
Ingredients
- 4 slices thick bread, such as Italian or rustic bread
- 1 tablespoon butter, for grilling
- ¼ cup finely diced onion and pepper mix, thawed
- 4 slices American cheese
- 1 cup leftover grilled steak or 4 slices deli-cut roast beef
Instructions
- Butter one side of each bread slice and set aside.
- Melt the butter on a griddle or skillet over medium-high heat. Add the onion and pepper mix, sauté for 3 to 4 minutes or until onions have softened. Add the leftover steak or roast beef onto the griddle or skillet and cook until warmed through. Remove from heat.
- Onto the griddle or skillet, place the bread slices butter side down and grill, until golden brown. Remove from heat and set aside.
- Once bread is ready, spread the onion and beef mixture on the griddle, separate into 2 sections and top with each section with 2 cheese slices. Once the cheese is melted, transfer each section onto a toasted bread slice, assemble the sandwiches.
- Serve immediately, or, to pack inside a lunchbox, wait for the sandwich to cool down to room temperature prior to slicing in half and packing inside the lunchbox.
Erika
I’m searching for school lunch ideas for my middle schooler. I love this idea but I always struggle with keeping the food warm for 3 1\2 hours until his school’s lunch time. Do you have any suggestions on “to go” bowls or theemos’, preferably reusable? Thank you for your recipes!
MOMables - Laura
A Thermos is one of the best purchases you can make to keep a hot lunch for hours! Here are my top Thermos Containers that I own and have tested.
MOMables-Laura
Hi Erika, I have suggestions for thermoses here: https://www.momables.com/top-5-thermos-containers-for-school-lunches/. You are welcome!