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Pale green-cream cardoon soup in a white bowl topped with Parmigiano, parsley and olive oil on linen

Zuppa di Cardi: Italian Cardoon Soup with Parmigiano

A cardoon soup simmered with onion, potato, and Parmigiano rind, then half-blended for a creamy body without cream. Serves 4 in about 80 minutes.
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Prep Time 25 minutes
Cook Time 55 minutes
Total Time 1 hour 20 minutes
Servings: 4 servings
Course: Soup
Cuisine: Italian
Calories: 196
Ingredients Method Notes

Ingredients
  

For the cardoons
  • 1 kg cardoon stalks (ribs) about 500 g after trimming, pale inner ribs
  • 3 tbsp lemon juice / 45 ml; from 1 lemon
  • 2 l cold water for soaking
  • 1.5 l water for boiling
  • 1 tsp fine sea salt for the boiling water
For the soup
  • 3 tbsp extra virgin olive oil / 45 ml
  • 1 yellow onion medium (150 g); finely chopped
  • 2 cloves garlic thinly sliced
  • 300 g Yukon gold potatoes peeled, cut into 2 cm cubes
  • 1 l low-sodium vegetable or chicken broth
  • 30 g Parmigiano Reggiano rind optional
  • 40 g Parmigiano Reggiano (about 1/2 cup); finely grated, plus more to serve
  • 2 tbsp fresh flat-leaf parsley chopped
  • 1/2 tsp fine sea salt plus more to taste
  • 1/4 tsp black pepper freshly ground

Method
 

  1. Fill a 4 L / 4-quart bowl with the 2 L cold water and the lemon juice. Cut the leaves and base off the cardoons, separate the pale ribs, and peel the strings from the rounded side of each rib with a vegetable peeler. Cut the ribs into 2 cm pieces and drop them into the lemon water as you go. Peel and cube the potatoes, chop the onion, and slice the garlic.
  2. Bring the 1.5 L water and 1 tsp salt to a boil in a 22 cm / 4-quart saucepan. Drain the cardoons, add them, and boil gently for 30 minutes, until a knife slides in with no resistance and the pieces have no fibrous threads. Drain well.
  3. While the cardoons boil, warm the olive oil in a 26 cm / 5-quart Dutch oven over medium-low heat. Add the onion and a pinch of the 1/2 tsp salt and cook for 8 minutes, stirring, until soft and pale with no browning. Add the garlic and cook for 1 minute, until fragrant.
  4. Add the potatoes, drained cardoons, broth, and Parmigiano rind to the Dutch oven. Bring to a boil, lower to a steady simmer, partly cover, and cook for 20 minutes, until a potato cube crushes easily against the side of the pot.
  5. Remove the rind. Blend about half the soup with an immersion blender in short pulses, leaving the rest chunky. Stir in the grated Parmigiano, parsley, pepper, and salt to taste, then thin with up to 60 ml hot water if it feels stiff. Serve hot with more cheese and olive oil.

Notes

  • Cardoons lose about half their weight in trimming, so buy roughly 1 kg for 500 g of usable ribs.
  • Prep the cardoons up to 24 hours ahead and keep them submerged in lemon water in the fridge.
  • Taste the broth first and hold back added salt until the Parmigiano goes in.
  • Loosen leftovers with hot water or broth, since the soup thickens in the fridge.