Instructions

1. 1
   After preparing the leeks, wash them very well in water to remove all traces of dirt and grit, which hide between the layers. Drain well.
2. 2
   Melt the butter in a large pot over medium heat. Add the vegetables, and season with a pinch each of salt and pepper. Stir to coat everything well with butter.
3. 3
   Cover the pot, and let the vegetables sweat over low heat for 10 minutes—make sure not to let them brown.
4. 4
   Stir in the chicken stock, and bring the pot to a boil. Simmer until the vegetables are cooked through.
5. 5
   Working in batches if necessary, purée the mixture using a hand- or full-size blender.
6. 6
   If you would like a very smooth soup, work the puréed mixture through a sieve into a clean pot—this is laborious, but it yields a velvety product.
7. 7
   Taste the soup, and season to taste with additional salt and pepper.