In a small bowl, combine the seasonings for the sandwich filling.
1 ½ tsp salt, ½ tsp ground black pepper, 1 ½ tsp garlic powder, ½ tsp paprika
Prepare the spread for the hoagie rolls by combining mayo and ketchup together.
3 Tbsp mayonnaise, 1 Tbsp ketchup
In a large skillet, sauté the sliced mushrooms, peppers and onions with butter on medium high heat.
8 oz mushrooms, sliced, 1 large green bell pepper, sliced, 1/2 red onion, sliced, 1 Tbsp unsalted butter, for sautéing
Season with 1/3 of the seasoning mixture and cook the vegetables for about 3-4 minutes, or until they are tender and lightly caramelized.
Once the veggies are caramelized, remove from the skillet. Set aside.
Add the thinly sliced steak to the skillet and cook on medium high heat for about 3-4 minutes, or until the steak browned. (Do not overcook, you can leave some pink on the steak.)
1 1/2 lbs steak, thinly sliced
Season the steak with the remaining seasoning blend. Then add the veggies back into the skillet and mix to combine.
Turn off the heat and layer slices of provolone cheese over the Philly cheesesteak mixture. Cover the skillet with a lid to allow the cheese to melt perfectly.
6 oz provolone cheese , sliced
While the cheese melts, toast your hoagie rolls to a golden brown in a separate skillet or in the oven. Once toasted, spread your prepared sauce generously onto each bun.
4 hoagie buns
With a spatula or spoon, scoop the cheesy Philly mixture onto the toasted hoagie rolls, evenly dividing the mixture between the four buns. (If you are not enjoying them all immediately, do not add the mixture to the buns to avoid soggy buns.)
Serve your Philly Cheese Steak Sandwiches immediately while it is still hot. Pair with your favorite sides and enjoy.