For the Soup

• 3 tablespoons olive oil
• 3 medium carrots, peeled and chopped into rounds
• 2 medium potatoes, peeled and chopped into 2 cm (¾ inch) dice
• 2 celery stalks, finely chopped
• 1 onion, finely chopped
• 2 garlic cloves, finely chopped
• ½ medium zucchini (courgette), cut in half lengthways and sliced into half-moons
• 120 g (4¼ oz) savoy cabbage, shredded
• 2 litres (7 fl oz/8 cups) vegetable stock or water
• 2 thyme sprigs
• 2 x 3 cm (1¼ inch) strips lemon zest
• sea salt flakes
• freshly ground black pepper

For the Pistou

• 75 g basil leaves
• 3 tablespoons extra virgin olive oil
• ½ teaspoon sea salt flakes, or more to taste
• 2 garlic cloves, chopped

Heat the oil in a large, heavy lidded pan and add the carrots, potatoes, celery and onion. Cook gently for about 12 minutes, stirring and turning the vegetables over every now and then. Add a splash of water if the vegetables start to stick to the pan. Add the garlic, zucchini and cabbage and cook for a few minutes more. Add the stock or water, thyme and lemon zest. Season with salt and pepper and gently simmer, covered, for about 10 minutes.

To make the pistou, blitz all the ingredients in a mini food processor, or pound in a mortar. Taste for seasoning.

To serve, ladle the soup into bowls and top with a spoonful of the pistou. Wonderful served with warm country-style bread.