
Preheat the oven to 400°F.
In a large skillet, heat 1 tablespoon of oil over medium-high heat. Add the onion, bell peppers, ½ teaspoon each of garlic powder and salt, and ¼ teaspoon of pepper. Cook, stirring occasionally, for about 10 minutes, until the vegetables are brown and caramelized. Remove the skillet from the heat and place the vegetables on a plate.
In a medium bowl, season the steak with the remaining 1 teaspoon of garlic powder, ½ teaspoon of salt, and ¼ teaspoon of black pepper. Toss it to coat evenly with the seasoning. .
To the same skillet, add the remaining 1 tablespoon of oil and heat it over high heat. Add the steak and spread it into an even layer. Cook, undisturbed, until the steak is browned, about 1½ minutes. Flip the pieces and cook until they are cooked through, about 1 more minute. Stir in vegetables to rewarm. Remove the skillet from the heat.
Meanwhile, open the rolls and place them cut side up on a baking sheet. Bake until they are lightly toasted, about 8 minutes. Remove them from the oven.
Divide the steak and vegetable mixture into 4 piles in the pan. Top each one with a slice of cheese. Cover and let the cheese melt for 2 to 3 minutes. (Return to low heat if necessary).
Place one section of meat and melted cheese into each of the rolls. Serve immediately.