A Philly cheesesteak doesn’t have to end up inside a roll.
These Griddle Philly Cheesesteak Stuffed Portobello Mushrooms take thin-sliced ribeye, onions, red bell pepper, provolone, and a tangy A1 steakhouse mayo and pile everything into griddled portobello mushroom caps.
The key is what happens on the griddle before those mushrooms ever get filled.
Instead of leaving the steak and vegetables in long strips, everything gets chopped down after cooking so the filling actually fits inside the mushroom caps. Every bite gets ribeye, peppers, onions, sauce, mushroom, and melted provolone instead of half the steak sliding out onto the plate.
It’s basically a loaded griddle cheesesteak with the mushroom doing the job normally handled by the roll.
Why Portobello Mushrooms Work So Well Here
Large portobello caps are sturdy enough to hold a real cheesesteak filling while bringing their own deep, savory flavor to the recipe.
Once they hit a hot griddle, the mushrooms soften, pick up some browning, and release excess moisture.
That last part matters. Stuffing raw portobellos with a hot steak mixture would leave you with a watery mushroom underneath all that good filling.
Cooking the caps first gives us a much better finished texture.
Ribeye Is the Right Beef for This Version
Thin-sliced ribeye is what I used here, and I’m keeping it.
The marbling gives the steak enough fat to stay tender during the quick, high-heat griddle cook, and shaved or very thinly sliced beef cooks in just a few minutes.
It’s the same reason ribeye works so well in the SG&G Ultimate Griddle Philly Cheesesteak.
You can buy shaved ribeye already sliced, or partially chill a ribeye before slicing it thin yourself.
Red Bell Pepper, Not Green
This version uses red bell pepper.
Red peppers are sweeter and a little softer in flavor than green bell peppers, which works particularly well with ribeye, onion, portobello, and the tangy A1 sauce.
They also bring great color to the filling without introducing another strong flavor that competes with the beef.
Why Everything Gets Chopped After Cooking
This is one of the most important details in the entire recipe.
Traditional cheesesteak filling can stay fairly loose because it’s going into a long roll.
A portobello cap doesn’t give us that kind of room.
Once the ribeye, onions, and red peppers are cooked, I use the griddle spatulas to chop everything together into smaller pieces.
We’re not trying to turn it into ground beef. We just want a compact chopped cheesesteak filling that can actually be spooned into the mushroom cap and stay there.
It also means every bite gets a better mix of steak and vegetables.
The A1 Mayo Was Worth Keeping
I added A1 steak sauce and mayo when I made these, and that combination stayed in the final SG&G version.
Straight A1 brings plenty of tang and savory steakhouse flavor, but mixing it with mayo rounds everything out and gives us a creamy sauce that can sit underneath the cheesesteak filling without overpowering the ribeye.
I like roughly two parts mayo to one part A1 as the starting point.
That leaves the beef as the main event while still giving you that steak-sauce flavor in the background.
Why Provolone Belongs on These
There are plenty of cheeses we could use, but provolone makes the most sense for this version.
It’s familiar in a cheesesteak, melts beautifully, and has enough flavor to stand up to ribeye, mushroom, peppers, onions, and A1.
We’re also using it where it has the most impact: right over the top of the stuffed mushroom.
The Broiler Finish Is Worth the Extra Step
The griddle does nearly all of the cooking.
The broiler has one job: finish the cheese.
Once the mushroom caps are packed with chopped cheesesteak filling, a slice of provolone goes over each one and the tray goes under the broiler just long enough for the cheese to completely melt and pick up a few lightly browned spots.
That gives the mushrooms a finished, loaded appearance without overcooking the steak on the griddle while you wait for cheese to melt.
Why This Is a Griddle Recipe
The flat top is doing all the important work here.
You’ve got room to cook the portobello caps on one section while the onions and peppers soften on another. Then the hotter side handles the thin ribeye.
Once everything is cooked, two spatulas make it easy to chop the steak and vegetables together into the smaller filling we need.
You could technically make all of this in skillets, but the griddle makes the workflow much easier.
Don’t Crowd the Ribeye
Thin steak cooks incredibly quickly.
Spread it across a hot portion of the griddle and give it room to brown instead of steaming in a pile.
Let it sear briefly before you start moving and chopping it.
If you’re doubling this recipe, cook the beef in batches rather than covering the whole griddle with cold meat at once.
Don’t Overcook the Mushrooms
Portobello caps need enough time on the griddle to soften and release excess moisture, but they still need enough structure to hold the filling.
You’re making an edible bowl, not mushroom pudding.
Once they’re tender with some browned edges but still hold their shape, move them off the heat and get the filling ready.
Can I Prepare the Filling Ahead?
Yes.
The ribeye, onion, and red pepper mixture can be cooked and chopped ahead of time, then refrigerated.
The A1 mayo can also be mixed ahead.
For the best mushroom texture, I would still cook the portobello caps closer to serving and assemble them before the broiler finish.
How to Make Them More or Less Saucy
The A1 mayo should support the cheesesteak rather than drown it.
Start with a thin layer inside each mushroom cap.
If you want more sauce, serve additional A1 mayo on the side instead of adding so much underneath the filling that the mushroom becomes slippery.
What to Serve With Cheesesteak Stuffed Mushrooms
For game day, these work well alongside wings, sliders, potato skins, or other foods that people can grab without sitting down for a full steak dinner.
If you want the traditional sandwich version on the same menu, the SG&G Ultimate Griddle Philly Cheesesteak uses the same hot-and-fast ribeye technique in a classic roll.
You can also use the full SG&G Game Day Recipes collection to build out the rest of the spread.
Frequently Asked Questions
Do I need to remove the portobello gills?
I recommend it. Scraping out the dark gills gives you more room for the cheesesteak filling and helps reduce some of the dark liquid portobellos release as they cook.
Can I use sirloin instead of ribeye?
Yes, but ribeye is my preferred choice for this recipe because its marbling keeps the thin steak tender during the fast griddle cook.
Can I use green bell pepper?
You can, but this SG&G version specifically uses red bell pepper. It’s sweeter and is the version I cooked and wanted to keep.
Do I have to use A1?
No, but it’s part of the flavor profile of this version. If you’re making the SG&G recipe as written, I’d keep it.
Can I use American cheese instead of provolone?
Technically yes, but provolone is the cheese I’m using here. It melts beautifully under the broiler and fits the ribeye and mushroom combination really well.
Can these be made without a broiler?
Yes. Put the stuffed mushrooms back onto a lower-heat section of the griddle, add the provolone, and cover them with a melting dome until the cheese melts. The broiler simply gives the cheese a little more color.
Can I make smaller appetizer mushrooms?
You can, but you’ll need to reduce the size of the filling even more. Large portobello caps are easier to stuff and give you a more substantial game day portion.
Why chop the filling after cooking?
Because the portobello cap has limited space. Chopping the cooked ribeye, peppers, and onions together lets you pack more balanced cheesesteak filling into each mushroom without long strips hanging over the sides.
A Cheesesteak Built for the Griddle
This isn’t trying to convince anybody that a mushroom is secretly bread.
It’s just a really good place to put cheesesteak filling.
Thin ribeye, sweet red peppers, onions, creamy A1 mayo, and provolone all fit naturally with the meaty flavor of a griddled portobello.
Chop the filling down, load the caps, melt the cheese, and put them on the table.
From Our Backyard to Yours.
Griddle Philly Cheesesteak Stuffed Portobello Mushrooms
Equipment
- Outdoor flat-top griddle
- 2 sturdy metal griddle spatulas
- Broiler-safe sheet pan or baking dish
- Sharp knife
- Cutting board
- Spoon for removing mushroom gills
- Small mixing bowl
- Pastry brush or silicone brush
- Tongs
Ingredients
For the Portobello Mushrooms:
- 6 large portobello mushroom caps
- 1 tablespoon neutral cooking oil
- 1/2 teaspoon kosher salt
- 1/4 teaspoon freshly ground black pepper
For the Cheesesteak Filling:
- 1 pound thin-sliced or shaved ribeye
- 1 medium yellow onion diced
- 1 medium red bell pepper diced
- 1 tablespoon neutral cooking oil
- 3/4 teaspoon kosher salt divided or to taste
- 1/2 teaspoon freshly ground black pepper
- 1 tablespoon A1 steak sauce
For the A1 Steakhouse Mayo:
- 1/3 cup mayonnaise
- 2 tablespoons A1 steak sauce
- 1/4 teaspoon freshly ground black pepper
For the Cheese:
- 6 slices provolone cheese
- Additional provolone cheese optional for a heavier cheese layer
Instructions
- Preheat the griddle with one side set to medium heat and the other to medium-high heat, approximately 375–400°F.
- Remove the stems from the portobello mushrooms.
- Use a spoon to gently scrape the dark gills from the underside of each mushroom cap. This creates more room for the cheesesteak filling and helps reduce excess dark mushroom liquid.
- Brush both sides of the mushroom caps lightly with neutral oil. Season with kosher salt and black pepper.
- Place the mushrooms rounded-side down on the medium-heat section of the griddle.
- Cook for approximately 4–5 minutes, until the mushrooms begin to soften and develop some browning.
- Flip the mushrooms so the cavity side is against the griddle.
- Continue cooking for another 3–4 minutes, allowing additional moisture to cook out.
- Remove the mushrooms once they are tender but still firm enough to hold the filling. Transfer them cavity-side up to a broiler-safe sheet pan.
- Add approximately 1 tablespoon neutral oil to the medium section of the griddle.
- Add the diced yellow onion and red bell pepper.
- Season lightly with some of the kosher salt and cook for approximately 5–7 minutes, tossing occasionally, until the onion is tender and the red bell pepper has softened and developed some browned edges.
- Move the cooked onions and red peppers to a cooler section of the griddle.
- Spread the thin-sliced ribeye across the hotter section of the griddle in a fairly thin layer.
- Season the ribeye with the remaining kosher salt and black pepper.
- Let the ribeye sear undisturbed for approximately 60–90 seconds.
- Use two metal spatulas to turn, separate, and begin chopping the ribeye.
- Continue cooking for approximately 2–3 minutes, or until the steak is browned and cooked through.
- Bring the cooked onions and red bell peppers back into the ribeye.
- Add 1 tablespoon A1 steak sauce to the steak and vegetables.
- Using both griddle spatulas, chop the cooked ribeye, onions, and red peppers together into smaller pieces. The mixture should be finely chopped enough to fit neatly inside the portobello caps while still keeping recognizable pieces of steak and vegetables.
- Toss the chopped cheesesteak mixture together until the A1 is evenly distributed, then remove it from the heat.
- In a small bowl, combine the mayonnaise, 2 tablespoons A1 steak sauce, and black pepper. Stir until smooth and creamy.
- Spread approximately 1–2 teaspoons of A1 steakhouse mayo inside each cooked portobello cap.
- Divide the chopped ribeye, onion, and red pepper mixture evenly among the six mushroom caps.
- Gently pack the filling into each mushroom so the caps are generously filled without piling the mixture so high that it falls off.
- Place one slice of provolone cheese over each stuffed mushroom. Fold the cheese slightly if necessary so it follows the shape of the mushroom cap.
- Preheat the oven broiler to high.
- Place the sheet pan approximately 5–6 inches below the broiler.
- Broil for approximately 1–3 minutes, watching continuously, until the provolone is completely melted and develops a few lightly browned spots.
- Remove the mushrooms from the oven immediately once the cheese is melted.
- Allow the stuffed mushrooms to rest for approximately 3–5 minutes before serving.
- Serve warm with additional A1 steakhouse mayo on the side if desired.
Notes
Thin-sliced or shaved ribeye is the preferred beef for this recipe. The marbling helps the steak remain tender during the quick, high-heat griddle cook. RED BELL PEPPER:
This recipe specifically uses red bell pepper instead of green bell pepper. Red pepper is sweeter and pairs especially well with ribeye, onion, provolone, A1, and portobello mushrooms. CHOP THE FILLING:
This is an important part of the recipe. Do not leave the steak, onions, and peppers in long cheesesteak strips. Once cooked, chop everything together on the griddle so the filling fits neatly inside the mushroom caps and every bite contains steak and vegetables. PORTOBELLO GILLS:
Removing the dark gills is recommended. It creates additional room for the filling and helps reduce excess dark liquid while the mushrooms cook. DO NOT OVERCOOK THE MUSHROOMS:
The portobellos should be tender but still sturdy enough to support the cheesesteak filling. A1 IN THE FILLING:
A small amount of A1 steak sauce is added directly to the chopped steak and vegetables to build savory steakhouse flavor without overwhelming the ribeye. A1 STEAKHOUSE MAYO:
The sauce uses roughly 2 parts mayonnaise to 1 part A1 steak sauce. Use a thin layer inside each mushroom rather than adding so much sauce that the filling becomes slippery. EXTRA SAUCE:
Serve additional A1 mayo on the side for anyone who wants a stronger steak-sauce flavor. PROVOLONE:
Provolone is the preferred cheese for this SG&G version. It melts smoothly and pairs naturally with ribeye and mushrooms. BROILER:
Watch the mushrooms continuously once they go under the broiler. The provolone can go from melted and lightly browned to burned very quickly. NO BROILER METHOD:
Return the stuffed mushrooms to a lower-temperature section of the griddle, top with provolone, and cover with a melting dome for approximately 30–60 seconds, or until the cheese is melted. MAKE AHEAD:
The ribeye, onion, and red pepper filling can be cooked, chopped, cooled, and refrigerated ahead of time. The A1 mayo can also be prepared up to 1 day ahead. ASSEMBLY:
For the best mushroom texture, cook the portobello caps and assemble the finished mushrooms closer to serving time. DOUBLE BATCH:
For 12 mushrooms, double all ingredients. Cook the ribeye in batches so the griddle stays hot enough to sear the meat instead of steaming it. STORAGE:
Refrigerate leftovers promptly in an airtight container and use within approximately 3 days. REHEATING:
Reheat in a 350°F oven, air fryer, or covered griddle until heated through. Add a fresh piece of provolone near the end if the original cheese has dried out. NUTRITION Estimated nutrition per stuffed portobello mushroom: Calories: approximately 430 Protein: approximately 31 g Carbohydrates: approximately 10 g Fat: approximately 31 g Saturated Fat: approximately 12 g Sodium: approximately 850 mg Sugar: approximately 5 g Fiber: approximately 2 g Nutrition is estimated and will vary based on ribeye, mushroom size, provolone, mayonnaise, A1 steak sauce, oil, and portion sizes.
