Tomato and basil are a classic flavour combination. The green basil oil provides a vibrant colour contrast to the orange-red of the soup base and elevates this humble tomato soup to something a little more refined.
1 bulb of garlic
Olive oil, for roasting
350g (about 1 large) fennel bulb, trimmed and quartered
Sea salt and freshly ground black pepper, to season
1 leek (white part only), roughly chopped
100g (about 2 sticks) celery, chopped
150g (about 1 medium) carrot, chopped
500g (about 4 medium) tomatoes, roughly chopped
1 x 400g can plum tomatoes
500ml vegetable stock
15g fresh basil
For the basil oil:
150ml olive oil, plus extra if needed
60g fresh basil
Sea salt, to taste
1. Preheat the oven to 200ºC (400ºF) Gas 6.
2. To roast the garlic, cut the top part off the top of the garlic head to expose the individual garlic cloves. Place the garlic head, cut-side down, onto a square piece of foil and drizzle with 2 teaspoons of olive oil. Lift the foil up around the garlic and place on a baking sheet. Roast in the preheated oven for 45 minutes. Remove from the oven, open the foil wrap and set aside to cool. When the garlic is cool enough to handle, squeeze the cloves out of the skin, coarsely chop the garlic flesh and discard the skin.
3. Place the quartered fennel in a roasting pan, drizzle with 1 tablespoon of olive oil and season with the salt and freshly ground black pepper. Cook in the same oven as the garlic for 25 minutes, or until you can easily insert the tip of a sharp knife into the flesh. Remove from the oven, set aside to cool slightly then roughly chop.
4. To make the basil oil, whizz together a little of the olive oil with the fresh basil and salt in a food processor. With the motor running, slowly drizzle in more oil until you have a loose, flavoured oil. Set aside until ready to serve.
5. Heat 2 tablespoons of olive oil in a large saucepan or pot set over a medium heat. Add the chopped leek, celery and carrot and gently cook for 10–15 minutes, stirring from time to time, until the vegetables are soft. Add the roast garlic and fennel, fresh and canned tomatoes and vegetable stock. Bring the mixture to the boil then reduce the heat and simmer for 45 minutes.
6. Remove the pan from the heat, stir in the basil leaves and purée with a handheld electric mixer or in a food processor. Season to taste and serve with a good drizzle of basil oil, some freshly ground black pepper, and garnish with fresh basil leaves.
Photograph: Kate Whitaker