Preheat the oven to 220°C, fan 200°C, gas 7. Cook the baking potatoes for 1 hour.
About 15 minutes before the potatoes are due to come out of the oven heat 3 teaspoons olive oil in a pan. Add the deseeded and sliced peppers, and cook for 10 minutes, until softened.
Pour the carton of chopped tomatoes into a pan and heat through. Add the tomato purée, dried mixed herbs and the peppers, and cook for 5 minutes, until thickened.
Spoon over the baked potatoes and top with torn mozzarella cheese.