Step 1

Preheat the oven to 400F. Spray a baking sheet with oil.

Step 2

Gently remove the stems, scoop out the gills and spray the tops of the mushrooms with oil, season with 1/8 tsp salt and fresh pepper.

Step 3

Season steak with salt and pepper on both sides.

Step 4

Spray a large skillet with cooking spray and heat on high, let the pan get very hot then add the steak and cook on high heat about 1 to 1 1/2 minutes on each side, until cooked through.

Step 5

Transfer to a cutting board and slice thin, set aside.

Step 6

Reduce the heat to medium-low, spray with more oil and saute onions and peppers 5 to 6 minutes, until soft.

Step 7

Combine all the ingredients in a medium bowl. Transfer to the mushroom caps, about 1/2 cup each.

Step 8

Bake in the oven until the cheese is melted and the mushrooms are tender, about 20 minutes.