- 2 tablespoons olive oil, divided
- 1 onion, cut into matchstick-size pieces
- 1 green bell pepper, cut into matchstick-size pieces
- 1 red bell pepper, cut into matchstick-size pieces
- 1 (4 ounce) package mushrooms, sliced
- 1 (10 ounce) package seitan, thinly sliced
- salt and ground black pepper to taste
- 4 hoagie rolls, split lengthwise
- 4 slices provolone cheese
- Preheat oven to 425 degrees F (220 degrees C).
- Heat 1 tablespoon oil in a skillet over medium heat; cook and stir onion, green bell pepper, and red bell pepper until onion is translucent, 5 to 10 minutes. Add mushrooms; cook and stir until tender, 5 to 10 minutes. Transfer vegetable mixture to a bowl.
- Pour remaining olive oil into the skillet over medium heat; add seitan and cook, turning frequently, until browned on all sides, 5 to 10 minutes. Return vegetable mixture to skillet and mix with seitan; season with salt and pepper.
- Arrange hoagie rolls on a baking sheet and fill with seitan-veggie mixture. Place 1 provolone cheese slice over the filling of each sandwich.
- Heat sandwiches in the preheated oven until cheese is melted, about 5 minutes.