Sweet Potato Vichysoisse with Chipotle Crema
4 cups sliced leeks, the white part
4 cups sweet potatoes or yams ( 1 1/2 pounds), peeled and roughly chopped
6 to 7 cups water
Kosher salt and freshly ground black pepper
1 cup crème fraiche, divided
2 tablespoons milk, if needed
1 tablespoon minced chives
2 teaspoons chipotle en adobo
1 ½ tablespoons tomato paste
Place the leeks, potatoes, water and 1 teaspoon salt in a soup pot and bring to a boil over high heat. Reduce to medium low and simmer until the vegetables are tender, 20 to 25 minutes. Let the soup cool completely. Puree the soup in batches in a blender until very smooth. If the soup is too thick, add ice cubes to the soup, a couple at a time, and continue to puree until the ice is melted and the soup is the consistency of very thick heavy cream. Season with salt and pepper. Add half of the crème fraiche and whisk to combine. Strain through a fine mesh strainer and place in the refrigerator until well chilled.
For the crema garnish, place the remaining 1/2 cup crème fraiche in a small bowl. Add the chipotle, 1 teaspoon at a time, until you get to the desired spiciness. Add the tomato paste and whisk together. Season with salt. If the crema is too thick, add water or milk, one tablespoon at a time, until you get to a pourable consistency.
To serve, ladle the chilled soup into bowls and drizzle the chipotle crema onto the top.