Chilled Sorrel, Potato, and Leek Soup

This take on the classic French cream of sorrel soup is packed with bright, lemony flavor. A garnish of sliced sorrel leaves adds an extra dose of tartness.

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  1 Tbs. unsalted butter
  
  


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  1 medium leek (white and light-green parts only), thinly sliced (about 1 cup)
  
  


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  Kosher salt
  
  


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  2 small Yukon Gold potatoes, peeled and cut into small dice (about 2 cups)
  
  


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  1 cup lower-salt chicken broth
  
  


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  4 oz. sorrel leaves, ribs removed; more for garnish
  
  


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  1 Tbs. plain yogurt
  
  


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  Freshly ground black pepper
  
  

Melt the butter in a 4-quart pot over medium-low heat. Add the leek and a pinch of salt and cook until tender but not brown, 5 to 7 minutes. Stir in the potatoes and then add 3 cups of water, the broth, and 1 tsp. salt. Bring to a boil, cover partially, reduce the heat to maintain a simmer, and cook until the potatoes are tender, about 12 minutes. Add the sorrel and cook until wilted, 1 to 2 minutes. Remove from the heat and let cool slightly.

Purée the soup in a blender until smooth. Pour the soup into a medium bowl, cover, and refrigerate until completely chilled, about 4 hours. Whisk the yogurt into the soup and season to taste with salt and pepper. Serve garnished with thinly sliced or chopped sorrel leaves.