Wash the peppers, cut off the tops and remove the seeds. Prepare a filling with all the remaining ingredients and stuff the peppers, not all the way to the top to prevent the filling from spilling during baking. Arrange the peppers in an oiled baking dish in a radial pattern with the stems facing the center. Drizzle with some olive oil, oregano, salt and pepper and bake at 180°C, turning the peppers once. Carefully peel before serving.