Stir in lemon juice at the very end, when the soup is no longer simmering.
Corn cobs fortify the base of this cold, creamy soup. Then the trick is to leave it simple, highlighting the taste of the corn and summer.
2 tablespoons extra-virgin olive oil
2 medium leeks, white and light-green parts only, coarsely chopped (about 1 1/2 cups)
5 ears shucked corn, kernels cut from cobs, cobs reserved
1 cup coarsely chopped peeled potato (about 1 medium)
4 cups good-quality vegetable stock
Kosher salt and freshly ground black pepper
1 tablespoon fresh lemon juice
1/4 cup crème fraîche or sour cream
1 tablespoon finely chopped fresh chives
1. Heat oil in a large heavy pot over medium heat. Add leeks and cook, stirring occasionally, until they begin to soften, about 5 minutes.
2. Add corn kernels, reserved cobs, potato, and stock. Season lightly with salt and pepper. Increase heat to high and bring soup to a boil. Reduce heat to simmer, cover with lid slightly ajar, and cook until the vegetables are very soft, about 35 minutes.
3. Discard corn cobs; let soup cool slightly.
4. Working in batches, purée soup in a blender until very smooth.
5. Set a fine-mesh strainer over a large bowl; strain, discarding solids.
6. Chill soup until cold. If too thick, thin with water by 1/4-cupfuls.
7. Stir in lemon juice, and season with salt and pepper.
8. Spoon a dollop of crème fraîche atop each serving and sprinkle with chives.
Originally published on Bon Appetit.