Clean your vegetables carefully. Peel the carrots, potatoes and turnip, but leave the skin on the zucchini (courgettes).

Shell the beans and soak them if necessary.

Cut the carrots, turnips, zucchini and potatoes into small cubes.

Boil the tomatoes to peel the skin and then crush them into large pieces.

Cut the leeks into thin strips and chop the onion.

In a large stockpot dish, cook the leek, onion and a crushed garlic clove in olive oil over low heat.

As soon as the onions and leeks become transparent, add all the vegetables except the beans and tomato. Cook for 5 minutes on low heat, stirring as necessary with a wooden spoon.

Pour in as much salted water as possible, add the beans and bring to a boil. Then lower the heat, cover and simmer for 1 hour.

Fifteen minutes before the end of the cooking time, add the tomatoes.

Use the pestle to crush three garlic cloves in the mortar.

Add the chopped basil leaves and continue to grind the mixture. When the garlic and basil are well blended, add the oil and grated parmesan and mix until you have a delicious sauce. If the pistou is too thick, you can add a small amount of hot stock to make it more liquid.

When serving, everyone should add a drizzle of raw olive oil before mixing with the pistou. Pour the pistou into the soup once it is off the heat or directly into the bowls. Stir and enjoy immediately.