Heat the olive oil on medium. Add the vegetables, arranging them so that they are all in contact with the oil. Cook until the onions soften and brown. Arrange the mushroom pieces together and place the slice of cheese over the mushrooms. Heat until the cheese melts. Layer on the roll with the mushroom slice on the bottom, then the red pepper, then the mushroom, covered with cheese.
Learn more about Mary's Meals.
Try it out: Select Mary's Meals are served daily in The Miriam Hospital cafeteria.