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Philly Style Mushroom Cheesesteak

  • Author: Cosette's Kitchen
  • Prep Time: 25
  • Cook Time: 20
  • Total Time: 45 minutes
  • Yield: 5 steak sandwiches 1x


A fun and simple meal to get the whole family involved using Campbell’s®. These steak sandwiches are very versatile!



Flank Steak

  • 1.5 pounds flank steak, trimmed*
  • 2 teaspoons kosher salt* (see note about salt below)
  • 2 teaspoons pepper
  • 3 Tablespoons olive oil
  • 2 Tablespoons red wine vinegar, or another similar vinegar
  • 1 teaspoon Italian seasoning
  • 1 heaping teaspoon toum, or 2 teaspoons garlic powder

Mushroom Sauce

  • 2 teaspoons toum, or 3 cloves garlic, minced
  • 1 can (10.5 oz) Campbell’s® Cream of Mushroom Soup
  • 1/2 cup of water
  • 1 teaspoon black pepper
  • 1 teaspoon dry or fresh thyme
  • 1/2 teaspoon kosher salt, adjust as needed*(see note about salt below)

Mushroom + Onion Mixture

  • 8 oz sliced cremini, white or Portobello mushroom
  • 2 large onions, sliced
  • 4 Tablespoons olive oil, divided
  • 1 Tablespoon toum, or 2 cloves garlic minced
  • Kosher salt as needed*

Other Ingredients

  • Kaiser rolls
  • Extra toum or olive oil for toasting bread
  • Blue cheese or your favorite cheese, provolone is also a great option
  • Hot peppers
  • Jalapeños 
  • Shredded cabbage or other green
  • Tomatoes
  • Mayonnaise
  • Anything else you’d like to include on your sandwich 


Flank Steak

  1. Prepare your flank steak by trimming any excess fat.
  2. Mix your marinade ingredients together and place in large sealed bag with flank steak. Allow to marinade for an hour over overnight.
  3. Be sure to remove your steak one hour before cooking to allow to come to room temperature for more even cooking. 
  4. If you have a cast iron grill pan, or any grill pan – you’ll want to use that. Otherwise, a traditional skillet works well. Heat your pan on high for 5 minutes until hot.
  5. Place your flank steak down and allow to sear for 2-3 minutes. You’ll know your steak is ready when you see grill/sear marks and browned.
  6. Flip and repeat on second side for 3-4 minutes.
  7. You can use a thermometer to check for doneness.
    Insert thermometer into the thickest part of the steak: 120F for very rare, 125F for rare and 130F for medium rare. You don’t want to cook beyond that.
  8. Remove pan from heat. Allow steak to rest for 10 minutes before slicing.

Mushroom Sauce

  1. In a small saucepan on medium heat, add your toum – if you are using minced garlic, add 1 teaspoon olive oil and heat garlic until JUST fragrant. Quickly add your soup and water.
  2. Whisk until just combined and add your seasonings.
  3. I always taste before adding salt, especially since the soup is already seasoned. Adjust accordingly.

Mushroom + Onion Mixture

  1. In a 10″ skillet, or something similar heat 2 tablespoons olive oil on medium-high heat. Add your onions and cook for 5 minutes until they begin to brown slightly and become translucent.
  2. Add a teaspoon of kosher salt* and continue to cook for another 5 or more minutes.
  3. I prefer my onions NOT to be fully caramelized for this dish but you certainly can continue cooking to caramelize. 
  4. Remove onions from pan, set aside.
  5. Add 2 tablespoons of olive oil into the same skillet on medium-high heat.
  6. Add your mushrooms and begin to cook for 3-4 minutes until they soften.
  7. As they begin to soften add your toum or minced garlic and cook for another 3-4 minutes. 
  8. Salt at the very END, salting early will release moisture into the mushrooms.
  9. Combine your onions and mushrooms and season as needed. Set aside.


  1. When you’re ready to enjoy your steak sandwiches, take your Kaiser or hard rolls and smear a bit of toum or olive oil on the inside. Place rolls on a sheet pan and into the oven on broil. 
  2. Allow the rolls to brown, this gives a good base for the steak sandwich components and won’t make it soggy.
  3. Once rolls are toasted, begin adding your ingredients –
    a smear of mushroom sauce
    a few slices of steak
    onion mushroom mixture
    more mushroom sauce
    shredded cabbage
    or whatever other toppings you’d like to include…
  4. Place filled sandwiches back into oven on broil for 3-4 minutes until tops are crisp and cheese melts.
  5. Enjoy!



  • Different types of salt have different levels of saltiness – I always season and taste along the way to make sure I have my flavors balanced. Kosher salt tends to be LESS salty than table salt. If using table salt, be sure to HALF the measurement and begin there.
  • An alternative to cooking a whole flank steak is to purchase pre-sliced carne asada or even thinly sliced beef. Season the same way and cook in a hot skillet in batches. 
  • All components can be made ahead and assembled the same you’re ready to eat.
  • Meat can be frozen up to 3 months in sealed packaging. I like to wrap in plastic wrap, then foil and pop into a sealed freezer bag for optimum freshness.

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