Preheat oven to 400 degrees
Prebake peppers on parchment line baking sheet for 10 minutes
Slice pepper in half lengthwise, remove ribs and seeds
Slice onions and mushrooms
Sauté over medium heat with butter, olive oil, and a little salt and pepper in skillet until caramelized
Salt and pepper steak and sauté in separate skillet for about 5 minutes
Add steak to the onion/mushroom mixture and stir to combine
Line inside of each pepper with a slice of provolone cheese
Fill each pepper with meat mixture until overflowing
Top each pepper with another slice of provolone cheese
Bake for 15-20 minutes until the cheese on top is golden brown