Steps
1. Preheat the oven to 350°F (175°C).
2. Cut off the top of the bread and hollow out the center, leaving a thick shell.
3. In a pan, sauté the onions until caramelized.
4. In a bowl, mix the mashed potato, caramelized onions, diced tomato, salt, and pepper.
5. Stuff the bread with the potato and onion mixture and cover it with the bread top.
6. Wrap the bread in aluminum foil and bake for 20 minutes.
7. Meanwhile, prepare the yogurt sauce by mixing yogurt, salt, and pepper in a small bowl.
8. Remove the bread from the oven, unwrap, and let it cool slightly.
9. Serve the stuffed bread with the yogurt sauce on the side.