2large leekswhite and light green parts only, thinly sliced
Kosher or fine sea salt
4large garlic clovesfinely minced
2teaspoonsfinely chopped fresh thyme3-4 sprigs
2poundspeeled and chopped pumpkin
4cupslow-sodium chicken or vegetable broth
Freshly ground black pepper
¼cupcrème fraichefor garnish
2tablespoonschopped fresh chivesfor garnish
One day before: Heat butter in a large soup pot over medium-low heat until it just begins to melt and bubble slightly. Add onion, leeks, and a pinch of salt. Cover and cook over medium-low heat for 8 minutes, stirring once, until soft and translucent. Add garlic and thyme and sauté, uncovered, for 2 minutes.
Add pumpkin and sauté for 3-5 minutes. Add broth and bring to a boil. Reduce heat to low and simmer, uncovered, for 20-30 minutes.
Carefully blend the soup in the pan with an immersion blender until very smooth. (Alternatively, carefully transfer the soup to a blender and puree until very smooth.) Once the soup is the desired consistency, bring back to a simmer for another 10-15 minutes, or until it has thickened slightly. Season with 1 teaspoon each of salt and pepper and stir in the champagne vinegar. At this point, you can let the soup cool slightly and then refrigerate for up to 8 hours.
Day of serving: Reheat. Spoon soup into serving bowls and top each with 1-2 teaspoons of crème fraiche and chives.