Why It Works
- Slowly simmering all the summer vegetables in one pot tenderizes them to the point of melting, for a comforting, rustic soup.
- Vibrant pistou—a French variant of Italian pesto sauce—wakes the rich but mild soup up with a blast of garlic and basil flavor.
The Genoese, it’s fair to say, got around. One of Italy’s historic Maritime Republics, the citizens of Genoa were renowned for their seafaring prowess. The story of their interactions with and influence on the greater Mediterranean and beyond could fill volumes, but I’m going to focus on one small aspect here: pesto sauce.
You know, we all know it, most of us (except for the garlic and basil haters out there) love it. Well, the French love it too. In Provence, a short jaunt in a merchant galley from the docks of La Superba, the Ligurian capital’s superlative nickname, pesto took hold with just a slightly adapted name and recipe. There, it’s called pistou, and it’s made from the same base ingredients—basil, garlic, and olive oil—but without the original’s inclusion of pine nuts and cheese. Many versions of Provençal pistou, instead, incorporate some vegetables, often fresh minced tomato, or a ladleful of the classic summertime soup that pistou is most famously served with.
The pairing is so classic that the soup gets its name from the sauce: soupe au pistou.
What’s In Soup au Pistou?
A comforting staple of summertimes in Provence, soupe au pistou features an array of sun-kissed produce. But, as with any homey medley of vegetables, there’s no one ingredient list that everyone follows. Generally, soupe au pistou contains:
- Beans in two or three forms: including fresh spring or Romano beans (those long, flat string-bean relatives), as well as fresh and/or dried shell beans (cranberry and other borlotti-type beans are a popular option, but not the only one)
- Onions or a relative, such as leeks
- Zucchini or other summer squash
- Potato, which I like to cut into the soup “grandma-style”
- Fresh tomato
- Carrots
- Optional cooked pasta shells or some other small shape
- Many other things that look good and aren’t too strongly flavored (maybe leave the turnips and rutabagas for another dish)
Serious Eats / Amanda Suarez
The preparation method for the soup is also flexible. Some cook it less so the vegetables retain their shape and float in a lighter broth. Others prefer it in the style of a thick vegetable stew, with all the bits and nubbins melting into each other, thickening the broth so it’s rich and rib-sticking, even if it’s completely vegetarian. I love the thicker, stewier version because, to me, it’s nothing short of sexy—melting vegetables all fresh and full of flavor, still bursting with vigor yet relaxing into sublime submission.
Oh—it also doesn’t have to be vegetarian. Some recipes include a hunk of salt pork in the pot.
My recipe is for the thicker, stewier version, and I leave out the pork to let the vegetables shine. However, you can easily alter it by shortening cooking times and/or adding chunks of fatty pork at the start.
The Power of Pistou
If your vegetables are good ones—ideally in season and at peak ripeness from a farm stand or market—the soup alone will be a wonder. However, it’s not exactly a flavor explosion. That’s where the pistou comes in. Pungent with spicy, funky garlic, grassy olive oil, and herbal basil, it wakes up the soup, a flavor firecracker that adds a fresh pop to every bite. Some people like to stir it into the pot, others let diners decide how much to add to their individual bowls. But stir it in you must, preferably along with a healthy grating of cheese for richness.
Serious Eats / Amanda Suarez
You don’t have to use the mortar and pestle like I do—though doing so gives me automatic authenticity points. I can imagine a beret-capped French grand-père or grand-mère observing me with marble mortar and olive wood pestle in hand and nodding approvingly. Oui, oui, they say. C’est bien comme ça. Voilà, l’authentique! And I try not to look too smugly pleased with myself as they heap on praise.
No, you don’t have to do that. You can use a blender or food processor, and it’ll still be good.
Either way, I recommend tossing the basil leaves in the freezer for a short bit first. The ice crystals that form during the quick freeze tenderize the leaves, making it easier to crush them, and the cold temperatures temporarily deactivate enzymes that cause the basil to turn brown as it’s chopped.
It’s a good thing the Genoese spread pesto wherever they sailed. This warming end-of-summer soup is the best celebration of it.
Serious Eats / Amanda Suarez
This French Vegetable Soup Is Summer’s Coziest Goodbye
Cook Mode
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For the Soup:
3 tablespoons (45 ml) extra-virgin olive oil
1 pound yellow onions (454 g; about 2 medium onions), diced
Kosher or fine sea salt
1 pound (454 g) shelled fresh cranberry beans (from about 3 pounds; 1.3 kg cranberry bean pods) or 8 ounces (227 g) soaked dried cannellini or cranberry beans (if dried, see notes for soaking instructions)
1 pound (454 g) string beans or Romano beans, stem ends trimmed and beans cut into 1/2-inch lengths
1 pound (454 g) zucchini, ends trimmed and cut into 1/2-inch pieces
8 ounces (227 g) carrots, peeled and cut into 1/2-inch pieces
8 ounces fresh tomato (227 g; about 1 medium tomato), cored and diced
3/4 pound (340 g) Yukon Gold (yellow) potatoes, cut into small chunks
For the Pistou:
4 medium cloves (20 g) garlic
Medium-coarse sea salt or kosher salt
2 cups (60 g) picked basil leaves (frozen if desired for easier pureeing and color retention)
1/2 cup (120 ml) extra-virgin olive oil
2 whole plum tomatoes (about 7 ounces; 200 g total), peeled, seeded, and minced
For Serving:
1 to 2 cups cooked pasta shells (optional)
Grated cheese, such as Gruyere, Comte, or Gouda, for serving
For the Soup: In a large Dutch oven or soup pot, heat oil over medium heat until warmed. Add onions and a pinch of salt and cook, stirring often, until softened but not browned, about 4 minutes. Add beans along with enough water to cover (about 1 quart/liter) and a large pinch of salt and bring to a simmer over high heat. Lower heat to maintain simmer and cook until beans are al dente (almost tender but still retain a slight bite), about 40 minutes (though time will depend heavily on the type of beans you use so check doneness and prioritize that over the time estimate).
Serious Eats / Amanda Suarez
Add string (or Romano) beans, zucchini, and carrots, along with enough additional water to cover; season with a generous pinch of salt. Bring to a simmer over high heat, then reduce heat to maintain simmer and cook until vegetables are very tender, about 1 hour.
Serious Eats / Amanda Suarez
Stir in tomato and potatoes and cook until potatoes are very tender, about 30 minutes. Top up with additional hot water as needed if the soup becomes too dry: The final consistency of the soup will depend on your preference, some people like it brothier, others thicker like a hearty stew. Season with salt.
Serious Eats / Amanda Suarez
For the Pistou: If using a mortar and pestle, crush garlic with a pinch of salt until sticky and pasty, and no chunks remain. Next, pound in basil, a handful at a time and adding salt as you go, making sure leaves are well pounded and no longer stringy or in large bits before adding the next handful; salt acts as an abrasive and helps break down the basil, but be careful not to add too much and make the pistou too salty. Pound in the olive oil, then stir in the minced tomato.
If using a blender or food processor, process garlic with the basil, olive oil, and salt until a smooth sauce forms. Stir in minced tomatoes.
Serious Eats / Amanda Suarez
To Serve: If using pasta, stir the cooked pasta into the soup, adjusting consistency with additional hot water if it’s too thick; season to taste with additional salt as needed. Ladle soup into serving bowls, passing the pistou and cheese alongside for diners to stir into their soups to taste.
Serious Eats / Amanda Suarez
Notes
If using dried beans, soak them in ample cold water with a large pinch of salt and a small pinch of baking soda for at least 8 and up to 24 hours. Drain before adding to the soup pot.
