Place a large cast-iron skillet or heavy-bottomed pan over medium-high heat and add 1 tablespoon of olive oil.
Add the julienned bell peppers, onions, and mushrooms to the skillet. Sauté for 5 to 7 minutes until vegetables are tender and edges are slightly caramelized. Remove vegetables from the skillet and set aside.
Add the remaining 1 tablespoon of olive oil to the same skillet, maintaining medium-high heat.
Spread the thinly sliced steak in a single layer in the skillet. Season immediately with garlic powder, salt, and pepper.
Sear the steak for 2 to 3 minutes without moving to develop a crust, then flip and cook for an additional 1 to 2 minutes until fully browned.
Return the sautéed vegetables to the skillet and toss with the steak to integrate the flavors.
Reduce heat to low and lay the provolone cheese slices evenly across the top of the mixture.
Cover the skillet with a lid for 60 to 90 seconds until the cheese is fully melted and viscous.
Portion the mixture into four individual bowls and serve immediately.