Soupe au Pistou (Provencal Summer Vegetable Soup with Basil Pistou)

Method

1. 1Prepare the beans. If using dried cannellini beans, soak 200 g overnight in cold water, then drain. (If using canned, use about 2 cans, 400–480 g drained, and skip the soaking.) Cover the soaked beans with fresh water and simmer for about 45 minutes, until tender, then drain, reserving the cooking liquid. The beans are the backbone of the soup, so cook them until creamy but not falling apart.
2. 2Build the soup base. Heat 3 tablespoons of extra virgin olive oil in a large pot over medium heat. Add 1 finely chopped onion and cook for 4–5 minutes, until soft and translucent but not browned. Add 3 chopped tomatoes (peeled if you like) and cook 3–4 minutes more, until they break down and lose their raw edge. This light tomato-onion base gives the soup its quiet background warmth.
3. 3Add the vegetables and water. Peel and dice 2 potatoes and add them to the pot with about 2 litres of water (the classic uses water, not stock, so the vegetables shine; use vegetable broth if you prefer). Bring to a boil, then lower the heat and simmer for 15 minutes. Trim and cut 200 g of green beans into short lengths, dice 2 zucchini, and add both. Season with salt and simmer another 15 minutes, until all the vegetables are tender but not mushy.
4. 4Add the beans and pasta. Mash about half of the cooked cannellini beans with a fork — this gives the soup a creamy body with no flour at all — and add them to the pot along with the remaining whole beans. Pour in 100 g of small pasta or broken spaghetti and simmer just until the pasta is al dente, about 8–10 minutes. Do not overcook the pasta, or the soup turns gluey. Add a little of the reserved bean liquid or water if it gets too thick.
5. 5Make the pistou. While the soup simmers, pound 3 cloves of garlic with a pinch of salt into a paste in a mortar (or use a food processor). Add 40 g of fresh basil leaves and pound until fairly smooth, then drizzle in 5 tablespoons (75 ml) of olive oil while pounding, and finally work in 50 g of grated Parmigiano-Reggiano. No pine nuts — that is the Provencal way, and what sets pistou apart from Genoese pesto. Keep the garlic raw; do not brown it, or the pistou turns bitter. Use fragrant basil at room temperature, so it releases its oils. These 5 tablespoons come on top of the 3 used for the soup base: add them a spoonful at a time until the pistou is a loose, glossy paste that slides slowly off the spoon.
6. 6Serve with the pistou stirred in at the table. Taste the soup and adjust the salt. The pistou is never cooked — heat kills the basil aroma and makes it bitter — so place a generous spoonful of pistou in the bottom or center of each bowl and ladle the hot (not boiling) soup over it, or pass the pistou separately so each guest swirls in their own. Finish with extra grated Parmesan, a drizzle of olive oil, and black pepper. Serve with crusty bread and a glass of Provencal rose. Keep the soup and pistou separate when storing, so the pistou stays fresh.