Place the rolls cut-side up on a baking sheet, brush with 2 tablespoons of the olive oil and bake until lightly toasted, 10 to 12 minutes.
Meanwhile, heat a large cast-iron skillet over medium-high heat. Season the steaks all over with salt and pepper.
Add the remaining 2 tablespoons olive oil to the skillet and cook the steaks until they reach the desired doneness, about 4 minutes per side for medium rare. Remove to a cutting board to rest.
Meanwhile, add the roasted peppers, garlic, onions and pepper flakes to the skillet. Season with a pinch of salt and pepper. Cook until the onions have started to soften, about 3 minutes. Add the tomato paste and cook for 30 seconds. Add the wine, stirring and scraping the bottom to deglaze, another 30 seconds. Add the stewed tomatoes, tomato sauce, pepperoncini and oregano. Bring to simmer and cook for a couple minutes to allow the flavors to come together. Remove from the heat and taste, adjusting the seasonings if needed.
Slice the steak and shingle over the top of the skillet. Sprinkle over the parsley and Parmesan cheese. Serve with the toasted ciabatta rolls.