Wash the peppers and cut away 1 side to form boats. Remove the seeds and drain the peppers well. In a bowl, mix a little oil and salt and smear it on the outside of the boats using a brush. Arrange them in a dry oven dish.
Stir well. Fill the peppers carefully with this mixture. Bake in a preheated 356°F (180 °C) oven for 20 min. with both heating elements on.
Then, turn the heat up to 428°F (220 °C) and leave only the top element on. Shortly before taking them out of the oven, add the slices of tomato on top.