By mid-August, the basil is no longer a garnish. It is a bush. The bunches at the market are cheap and enormous, and by the time you get them home, the leaves are already threatening to blacken in the fridge. Soupe au pistou is the Provençal solution to exactly this problem: a pot of summer vegetables and white beans, finished at the table with a raw garlic-and-basil paste that you stir in yourself. It is not a basil soup. It is a vegetable soup with basil as the final, uncooked gesture.
The dish belongs to the same family as Italian minestrone and Genoese pesto, but it is not either of them. The pistou is basil, garlic, salt and olive oil, pounded or blended without pine nuts and without cheese in the pot. Cheese is passed separately, usually grated Gruyère or Parmesan, and each person adds it to their own bowl. That detail matters: it keeps the basil green and the broth clear, and it lets the table decide how rich the soup becomes.
What goes in the pot
The soup itself is built on what is ripe at the same moment as the basil. In Provence that means flat green beans, courgettes, potatoes, fresh shelling beans or dried white beans, and tomatoes. Some households add a handful of short pasta or broken vermicelli; others leave it out. Onions, leeks or a piece of bacon rind may go in for depth. The constants are the beans, the summer vegetables, and the pistou added off the heat.
A workable proportion for four to six people, metric first:
- 250 g dried white beans (cannellini or haricots blancs), soaked overnight, or 400 g cooked beans
- 1.5 litres water or light vegetable stock
- 2 medium potatoes (about 300 g), peeled and cubed
- 2 medium courgettes (about 400 g), cubed
- 200 g flat green beans, topped and cut into short lengths
- 3 ripe tomatoes (about 400 g), peeled, seeded and chopped, or 400 g tinned chopped tomatoes
- 1 onion, finely chopped
- 1 small leek, white part only, sliced
- Salt and black pepper
For the pistou:
- 60 g basil leaves, packed, stems removed
- 2 to 3 garlic cloves, depending on size and your tolerance
- 1 tsp fine salt
- 80 to 100 ml good olive oil
Grate 60 to 80 g Gruyère or Parmesan to pass at the table. If you want pasta, add 60 g broken vermicelli or small macaroni in the last ten minutes.
Method, with the timings that matter
If using dried beans, drain the soaked beans, cover with fresh water and simmer until nearly tender, about 45 to 60 minutes depending on age. Do not salt the water at the start; salt slows the softening. Drain, reserving the cooking liquid.
In a large pot, soften the onion and leek in a little olive oil over medium heat for 8 to 10 minutes, without browning. Add the tomatoes and cook for 5 minutes, until they collapse. Add the beans, potatoes, green beans and 1.5 litres of water or stock, plus enough of the bean cooking liquid to cover everything by about 2 cm. Bring to a simmer and cook for 20 minutes.
Add the courgettes and continue simmering for 15 to 20 minutes, until all the vegetables are tender but not collapsing. If you are adding pasta, do it now and cook until al dente, about 8 to 10 minutes. Taste and season with salt and pepper. The soup should be slightly thin; it will thicken as it stands.
Make the pistou while the soup finishes. Pound the garlic with the salt in a mortar until it forms a paste, then add the basil a handful at a time, grinding it into the garlic. Add the olive oil gradually until you have a loose, bright green sauce. A blender or small food processor works, but pulse it and scrape down the sides; prolonged blending warms the basil and dulls the colour. If the pistou is stiff, loosen it with a spoonful of the hot soup.
Take the pot off the heat. Stir two-thirds of the pistou into the soup, then taste. Add the rest if you want a stronger basil presence. Serve in warm bowls with the grated cheese and, if you like, slices of toasted country bread rubbed with garlic.
What usually goes wrong the first time
The most common mistake is adding the pistou to a boiling pot. Basil is a tender leaf; heat destroys the volatile oils that make it smell like basil rather than like cooked grass. Stir it in off the heat, and accept that the soup will not be as green as the pistou itself.
The second is overseasoning the pistou. The salt in the paste is there to help grind the leaves, not to season the whole pot. Salt the soup first, then add the pistou, then taste again.
The third is a thin, watery broth. This is not necessarily wrong; soupe au pistou is a soup, not a stew. But if you want more body, mash a ladleful of the beans and potatoes against the side of the pot and stir them back in. Do not add flour or cream. The starch from the beans is the correct thickener.
The fourth is cheese in the pistou. Leave it out of the paste. Cheese in the pot makes the broth cloudy and can turn stringy when reheated. Pass it at the table.
Regional and seasonal notes
The dish is associated with Provence and with the Nice hinterland in particular, where it is sometimes called soupe au pistou and sometimes pistou alone. The word pistou comes from the Provençal pista, to pound, which is also the root of the Italian pesto. The two sauces diverged: Genoese pesto traditionally includes pine nuts and pecorino, while Provençal pistou is basil, garlic, salt and oil. That is a culinary distinction rather than a documented rule, and households vary.
Vegetable choice follows the garden. Inland Provence may use fresh shelling beans such as cocos or borlotti; the coast may lean on courgettes and tomatoes. Some cooks add a piece of salt pork or a ham bone. In Nice, the soup is sometimes served with pasta cooked separately and added at the end, so it does not starch the broth. None of these variations is a deviation; they are the dish working as it was designed to work, with what is ripe.
Soupe au pistou is a named, recognised Provençal preparation; archival broadcast references could not be verified for this article. The broader point stands: this is not a generic vegetable soup with basil stirred in.
Substitutions for non-French kitchens
Dried cannellini beans are widely available and behave like French haricots blancs. If you can only find tinned beans, add them in the last ten minutes so they do not disintegrate. Flat green beans can be replaced with regular green beans or Romano beans. Courgettes are zucchini; choose small ones, as large ones are watery and seedy. If basil is expensive or tired, use what you have and increase the garlic slightly, but do not substitute dried basil in the pistou. It will not work.
For the cheese, Gruyère is the traditional pairing in many Provençal households; Parmesan is a common substitute. A aged Comté also works. Avoid soft cheeses, which clump.
Serving and keeping
Serve the soup hot but not boiling, with the pistou stirred in at the last moment. It is better the next day, but the basil will fade. If you are making it ahead, keep the pistou separate and stir it in after reheating. The soup freezes well without the pistou for up to three months.
This is a dish for the moment when the basil arrives faster than you can use it. It asks for a large pot, a mortar or a small blender, and about an hour of unhurried attention. The reward is a bowl that tastes like the end of summer in Provence, even if your kitchen is nowhere near it.
Questions that come up
Can I make pistou in a food processor? Yes, but pulse and scrape. Continuous blending heats the leaves and turns the sauce dull and bitter.
Do I have to use a mortar? No. A mortar gives a more textured, fragrant paste, but a small blender or immersion blender works. Add the oil slowly.
Is soupe au pistou vegetarian? It can be. Leave out bacon or ham bone and use vegetable stock. The cheese is optional at the table.
Can I use tinned beans? Yes. Add them near the end, as they are already cooked and will break down if simmered too long.
Why is my pistou brown? Oxidation and heat. Keep the basil cold, work quickly, and add the pistou off the heat. A squeeze of lemon juice in the paste can slow browning, though it is not traditional.
What do I do with leftover pistou? Spread it on bread, stir it into scrambled eggs off the heat, or spoon it over sliced tomatoes. It keeps in the fridge for two or three days with a film of oil on top.







