Watercress Buttermilk Vichyssoise
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5 from 1 vote

Watercress and Buttermilk Vichyssoise: #ProgressiveEats

The prep and cook time do not include time to chill the soup in the refrigerator.
Prep Time20 mins
Cook Time25 mins
Total Time45 mins
Course: Soup
Author: Susan Pridmore


  • 2 Tbsp unsalted butter
  • 1 cup finely diced sweet onion
  • ½ cup thinly sliced leeks – white and very very light green parts only
  • 2 cups thinly sliced Yukon potatoes
  • 1 tsp chopped garlic
  • 2 cups vegetarian broth
  • 3 bunches watercress leaves and stems chopped (about 6 cups, chopped)
  • 1 cup buttermilk
  • 1 ½ tsp kosher salt
  • ½ tsp white pepper
  • 2 Tbsp mascarpone cheese
  • pinch kosher salt
  • 1/2 tsp lime juice or to taste


  • Melt the butter in a heavy bottomed pot over medium heat - I use my Le Creuset for this. Add the onion and leeks and reduce the heat to medium-low. Put a lid on the pot and cook the onions and leeks until soft - about 15 minutes. At this level of heat, it's more sweating than sautéing - be careful not to brown!
  • Add the potatoes and garlic. Replace the lid to the pot and cook for another 5 minutes.
  • Add the broth and watercress, and bring to barely a simmer. Cook for 5 minutes, and pour the soup into a blender. I use my Ninja blender for this. Purée the soup and pass through a food mill if desired. The food mill will ensure that any stems remaining are removed.
  • Stir in the buttermilk, salt and pepper. The soup may taste under salted, but when chilled it will be fine. Chill for a few hours or ideally overnight before serving.
  • Whip together the mascarpone cheese, salt and lime juice with a small whisk or fork. Drop a 1/2 teaspoon dollop of cheese on each soup shooter.