Meaty portobello mushrooms star alongside sauteed onions and peppers topped with provolone cheese then stuffed into toasted garlic bread rolls in this tasty veggie version of a Philly Cheesesteak sandwich.

Veggie Philly cheesesteak sandwiches: a vegetarian sandwich for mushroom lovers.
Portobello Mushrooms make an excellent swap for meat in this vegetarian sandwich, and it could easily be made vegan by substituting the provolone cheese and butter for your favourite vegan alternative.
Pan seared portobello mushrooms, slow cooked caramelized onions, crisp and sweet peppers, and a healthy dose of Provolone cheese give this sandwich a wonderful depth of flavour.
For more cheesy vegetarian sandwich inspo check out our halloumi sandwich and roasted vegetable sandwich!
How to make a veggie Philly cheesesteak
First, you are going to want to start by carmelizing the onions.
Heat a large skillet to medium low heat and add some butter to it before adding in the sliced onions. Pro tip here: the thinner you slice the onions the quicker it is to get that sweet caramelized flavour out of the onions. Sprinkling a pinch of fine sea salt on the onions will not only season them but help them to release their moisture which in turn cooks them faster.
It should take about 20 minutes, but you will know that the onions are ready when they reach a nice deep golden colour.
Once your onions are ready, remove them from the pan and add the cooking oil and the sliced portobellos along with a pinch of fine sea salt. Again the sea salt here is to season, but also reduce the moisture. You want a nice meaty texture to the portobellos along with a bit of golden caramelization for flavour and the removal of moisture is key to both of those.
When the mushrooms have browned and reduced, add the sliced peppers and the caramelized onions to the skillet along with the tamari and cook until the peppers have heated through but still have a bit of a crunch to them - about 2-3 minutes.
To toast the bread and put together the sandwiches, heat your oven to 400℉.
Mix together the 1.5 tablespoon of butter with the 2 cloves of garlic and spread on both sides of the interior of the roll. Toast the bread for 3-5 minutes, or until the butter melts and the bread begins to crisp before removing it from the oven.
Spread out the mushroom and veggie mixture on the bottom half of the bread and top with the provolone cheese slices.
Put the sandwich back into the oven until the cheese melts. Remove from the oven and serve.
Tips for the Best Veggie Philly Cheesesteak
Thinly slice the onions so that they will caramelize faster.
The gills of the mushrooms can give everything a brown colour. Remove before cooking (like I did) If you don't want that.
The larger the skillet, the more surface area there is for cooking the mushrooms and giving them their best flavour. Use the biggest one you can find!
Dietary Considerations
This recipe for veggie Philly cheesesteak is suitable for the following diets:
- vegetarian
- vegan (swap out the butter and cheese for vegan alternatives)
- drop the bread and try the mushroom filling on a lettuce wrap for a low carb and keto friendly meal
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More Comforting Vegetarian Favourites You'll Love!
If you like this veggie Philly cheesesteak recipe, you might want to check out some of our other vegetarian recipes:
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Veggie Philly Cheesesteak
Ingredients:
- 1⁄2 large white onion - thinly sliced
- 1 Tablespoon butter
- 2 large portobello mushrooms - thinly sliced
- 2 Tablespoons cooking oil
- 1⁄4 green pepper - sliced
- 1⁄4 red pepper - sliced
- 1 Tablespoon tamari
- 1 large french sub roll - or 2 smaller rolls
- 2 cloves garlic - crushed
- 1.5 Tablespoon Butter
- 3 ounces thinly sliced provolone chese
- salt and pepper
Instructions
- Heat a large non stick pan over medium-low heat and add 1 tablespoon butter. When the pan is heated, add the sliced onions and a pinch of salt.
- Cook the onions for about 20 minutes or until they start to brown then remove them from the pan.
- Increase the heat to medium and add the cooking oil. Add the sliced portobello mushrooms to the pan and cook for about 10 minutes, or until they have released their moisture and begun to brown.
- Add the tamari, and a splash of water if the pan is getting dry, then add the peppers and cooked onions to the pan. Saute for about 5 minutes, or until the peppers have become tender. Season well with sea salt and pepper.
- Heat your oven to 400℉
- Mix the crushed garlic into 1.5 tablespoon butter and brush onto both sides of the sub roll. Bake in the oven for 5 mins or until the butter melts and the roll begins to toast.
- Remove the roll from the oven and top with the mushroom mixture then cover it with slices of the provolone cheese.
- Place the roll back in the oven and toast until the cheese melts.
- Remove from the oven and serve!
- Line each roll with provolone slices and top with the mushroom mixture.
- Serve
Nutrition
* nutritional information is calculated by online tools and may not be 100% accurate.
Katie says
These look so good! I love a good sandwich, and this one has so many flavors and textures. Yum!
Sabrina says
This sandwich looks fully loaded! Adding this to our meatless Monday dinner routine!
Tayler says
I will totally try this out on a gluten-free hoagie bun! It looks so delicious and I am loving the flavor combos
Amy | The Cook Report says
Such a great idea to use mushrooms instead of steak in this sandwich!
Lucy Parissi says
This looks like a fantastic rendition of the Phillly Cheesesteak. I love your addition of tamari for a little extra depth and richness.
Kelly says
One of the best Philly/vegetarian sandwiches I’ve ever had !!
Thanks Courtney!!
Courtney says
You're so welcome! I am so glad to hear you enjoyed it!
paula says
I’ve made this twice and it’s so simple and delicious. The tamari really elevates the flavor. I used a brioche bun, which was amazing, and added extra red and green peppers since I had them. Leftovers were so yummy the next day. This recipe is definitely in my regular rotation now.