Turn your oven on now so that it's pre-heated ready to cook later on! Heat settings are 200°C / 400°F .
First, peel the tomatoes. Do this by making a small cut in the skin then plunging the tomatoes in boiling water for 1 minute.
Run cold water over the tomatoes and the skins can then easily be peeled off. Cut the peeled tomatoes in half with a sharp knife, avoid squashing them.
Peel and finely chop the garlic. Place the halved tomatoes on the baking tray, cut side upwards. Sprinkle the garlic over the tomatoes and spread the basil leaves over the top.
Sprinkle two tablespoons of olive oil over the basil and tomatoes. Place the baking tray in the middle of the oven and leave it there for an hour.
Peel and finely chop the onions. 40 minutes before the tomatoes are roasted take the tray from the oven and sprinkle the chopped onion over the tomatoes. Put the baking tray back in the oven.
20 minutes before the tomatoes are roasted, peel the potato, chop it into four and place it in a pan with carrots and 470 ml (1 pint) cold water. Place the pan on the stove and bring to a gentle boil.
When the tomatoes are roasted, take the potato and carrots off the heat and mash coarsely with the water.Add the tomatoes to the pan of potatoes and remash. Add the tomato paste, a couple of shakes of Lea and Perrins and season with salt and pepper to taste.
Leave the blended soup in the pan and gently reheat for around 5 minutes stirring every minute or so. Don't let the soup boil.
Taste the soup and add any more salt or pepper according to taste.
Serve in warm soup bowls and garnish with a couple of basil sprigs if any is left.