Check out this Vegetarian Portabella Mushroom Cheesesteak Recipe from Oh My Veggies.
2 tbsp. olive oil, divided
2 extra-large portabella mushrooms, thinly sliced
2 tbsp. red wine
1 small green pepper, thinly sliced
1 large onion, thinly sliced
Salt and pepper, to taste
8 slices provolone or mozzarella cheese
4 sub rolls, sliced lengthwise (don’t completely cut the top from the bottom, though!)
1. Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add mushrooms and cook 3-4 minutes, or until softened and browned. Add wine and increase heat to high. Cook until liquid has evaporated, about 2-3 minutes. Transfer to bowl.
2. Preheat oven to 250 degrees.
3. Carefully wipe skillet clean. Heat remaining tablespoon of olive oil over medium-high heat. Add green pepper and onions; cook until softened, about 5-8 minutes.
4. Reduce heat to low. Return mushrooms to skillet and stir to combine, then season to taste with salt and pepper. Top vegetable mixture with cheese slices. Once cheese has melted, remove from heat.
5. Divide veggie mixture into sub rolls. Wrap each cheesesteak tightly with foil and place on a baking sheet. Bake for 15 minutes. Remove from oven and unwrap carefully.
If you are bothered by such things, you can remove the gills from the mushrooms before cooking them. They have a tendency to discolor the bread and onions a little.