Rustic Pistou Soup
By Emma
Certified Culinary Professional
•
Recipe tested & approved
A medley of summer vegetables simmered in savory broth, brightened by a punchy homemade pistou of basil, garlic, tomato, and cheese. Haricots blancs and green beans add texture. Potato and zucchini purée enrich body, balancing earthy sweetness with fresh herbs. Traditional French origins with tweaks for deeper aroma, creamier mouthfeel, and easier timing cues.
Prep:
25 min
Cook:
35 min
Total:
60 min
Servings:
6 servings
#French Provençal
#vegetable soup
#summer recipe
#slow simmer
#pistou
Forget slick purees and overworked sauces. This pistou soup is about layers, texture, stubborn bits that hold their shape through long simmers. The thickened broth carries the summer garden in every spoonful, punctuated by the punchy basil, garlic and cheese salsa lurking at the end. I learned early on to swap parmesan for pecorino – sharper, saltier, stands up better to cooking heat. Cooking times are more guidelines than gospel. Watch the potatoes soften and zucchini keep their bite; that’s the kitchen language here. The pistou? Best made fresh, coarse, slightly chunky to grip the broth hues instead of melting away. This is comfort but not dull - rustic but not sloppy. Each step has a purpose. The onion needs slow coaxing for sweet flavor, the beans need just a gentle touch of heat. I sizzle, mash, simmer, taste and balance like a scientist and a poet combined.
Ingredients
- 1 medium onion, finely chopped
- 80 ml olive oil (about 1/3 cup plus 1 tbsp)
- 1.2 liters rich vegetable or chicken broth (4 3/4 cups)
- 2 small zucchini, cut into chunks
- 1 medium sweet potato, peeled and cubed
- 1 large carrot, peeled and diced
- 240 ml drained canned cannellini beans (just under 1 cup)
- 250 ml green beans, cut into 2 cm (3/4 in) segments
- 60 ml fresh pecorino romano, finely grated (substitute for parmesan)
- 4 cloves garlic, peeled
- 2 large ripe plum tomatoes, coarsely chopped
- 110 ml packed fresh basil leaves (about 1/2 cup)
- Salt and freshly cracked black pepper
About the ingredients
An onion forms the flavor base, gently sweated, never browned to avoid bitter notes. Olive oil from first press elevates the rustic character; it’s not just fat but aromatic carrier. Broth must be hearty - homemade or quality storebought stock is a go-to for deeper complexity; vegetable broth works if richer than usual. Zucchini and potatoes provide body but different textures so keep their pieces whole enough to mash into rustic lumps that thicken broth without turning gooey. Sweet potato adds subtle sweetness balancing acidity from tomatoes in the pistou. Cannellini beans add protein and creaminess; rinsed but not soaked preserves bite. Green beans add crunch and bursts of chlorophyll freshness. Pecorino romano shines brighter than parmesan for punch and salt but swap in parmesan if needed. Fresh garlic and bunches of basil fresh off the stems season the pistou; frozen basil dulls the zip. Ripe plum tomatoes release juices but avoid watery types - more flesh is better. Salt and freshly crushed black pepper essential, but add gradually to avoid salty soup. Pro tip: basil bruises easily; handle gently to keep aromas intact.
Method
- Heat 2 tbsp olive oil in a heavy-bottomed pot over medium heat. Add onion. Sizzle, stirring often till translucent but not brown - about 6 minutes. The slow softening aroma signals readiness.
- Pour in broth, then toss carrot, zucchini, and sweet potato cubes. Bring up to a gentle boil, then reduce heat to low simmer. Cover. Bubble quietly for 22 minutes. Check when potatoes are soft enough to pierce and zucchini yielding but intact.
- Use slotted spoon to fish out zucchini and sweet potato. Smash them roughly with a potato masher or fork – aim for a rustic mash, not puree. Return mash to pot. Stir in beans and green beans.
- Simmer uncovered another 6 minutes. Beans should soften but not lose snap. Taste broth occasionally; adjust salt and pepper. The smell changes here – more vegetal sweetness.
- In a mortar and pestle or mini food processor, blitz garlic with pecorino, tomatoes, and fresh basil. Drizzle in remaining olive oil steadily. Look for a thick, grainy sauce. Don’t overblend or it’ll turn watery.
- Fold pistou into the soup. Stir gently to amalgamate flavors. Let sit off heat 3 minutes so aroma settles. The oil floats slightly, glossy on surface. Taste and tweak salt or more basil if needed - freshness fades fast.
- Serve warm. Garnish with extra grated cheese or basil sprigs if you like. Should be thick but spoonable. Leftovers deepen in flavor next day.
Cooking tips
Onions need patience. Medium heat, frequent stirring, until translucent and soft is key; anything higher risks bitter edges that spoil soup’s finesse. Add broth and veggies, bring to a slow simmer, not rolling boil, to break down roots gently while preserving freshness in zucchini. Check potato softness with fork - it should slide through easily but still hold a shape. Remove zucchini and potato for mashing - mash somewhat chunky to keep resistance; pureeing totally will dilute final mouthfeel. Return mash with beans back to pot to round flavors. Beans only require short reheating - overcooking makes them mealy and dull. The pistou blends raw aromatics to finish - blending too long thins it out, so stop while still coarse. Folding pistou in off heat avoids cooking away nuanced fresh notes. Let the soup rest briefly; multi-dimensional aromas should bloom. Season last and taste twice. This soup thickens on standing, so if too dense, a dash more broth or water fixes consistency. Serve hot or room temp anytime. Leftovers benefit from gentle reheating with splash broth to revive flavors.
Chef's notes
- 💡 Onion prep makes or breaks flavor. Sweat slow on medium heat, stirring often till translucent. No browning or bitterness. Smell shifts to soft sweet, signals ready. Add broth right away after, no waiting. Onion aroma carries base layers, don't rush. Tried faster, lost sweetness completely.
- 💡 Simmer veggies gently not boiling hard. Roots need longer, zucchinis shorter. Watch textures - potato pierces easily when done. Zucchini tangles soft but intact. Remove with slotted spoon first. Mash roughly - not puree. Retain chunky bits, add rustic body. Pureeing thins mouthfeel down; no grip left.
- 💡 Pistou blitz is sensitive. Garlic with pecorino, tomatoes, basil first. Add oil steady, slow drizzle. Watch for thick, grainy texture. Overblend and water seeps out, dulls flavor & texture. Fresh basil matters; frozen kills brightness. Handle basil gently - bruise kills aroma fast. Bring pistou in off heat only. Heat blunts fresh notes so quick.
- 💡 Season slow and last in steps. Salt earlier but taste broth last after pistou folds in. Pistou adds salt from cheese and basil freshness. Black pepper cracked freshly adds sharp snap but add less early. Soup thickens on standing; dilute with splash broth or water if needed. Leftovers reheat with additional broth for reviving flavors and balancing salt.
- 💡 Bean timing critical. Cannellini rinsed, not soaked. Beans add creamy texture but snap must stay. Reheat beans only short time after mash return. Overcooked beans turn gluey and dull flavor. Green beans add crunch—treat like vegetable, not mush. Watch carefully during second simmer, stir to avoid sticking. Timing varies with bean freshness and size.
Common questions
Can I use frozen basil?
Avoid frozen for pistou. Fresh basil bruises easily but keeps aroma. Frozen dulls freshness and flavor flat. If no fresh, use dried sparingly but taste shifts. Better to skip basil than freeze basil here.
What if potatoes overcook?
Mushy potatoes thin broth and lose rustic chunks. Salvage by mashing while still chunky not watery. Add more broth or beans to thicken. If very soft, serve soon before soup turns gluey. Otherwise reduce simmer time on next try.
How to store leftovers?
Soup keeps well refrigerated for 2-3 days. Cool quickly; seal tight. Reheat gently with splash broth so pistou flavors don’t cook away. Freeze in portions but pistou won’t keep same bite frozen; add fresh pistou on thawing if possible.
Can broth be substituted?
Rich vegetable broth best but good chicken broth works too. Avoid watery broths - soup needs body. Storebought stock ok if high quality. If weak broth, concentrate by reducing slightly before adding veggies. Adds depth without extra seasoning fuss.
