Vichyssoise (Cold Leek and Potato Cream Soup)

Method

1. 1Clean and slice the leeks. Trim off the dark green tops and the root ends of 4 leeks, keeping only the white and pale-green parts — the dark green is bitter and fibrous. Slice them lengthwise, then crosswise, and rinse thoroughly under running water, fanning the layers apart, because grit hides between them. Drain well. Properly cleaned leeks are the difference between a smooth soup and a gritty one.
2. 2Sweat the leeks without browning. Melt 50 g of butter in a heavy pot over medium-low heat. Add the sliced leeks with a pinch of salt, cover, and sweat gently for 10-15 minutes, stirring occasionally, until soft and translucent but with no color at all. This is the key step for vichyssoise: the soup must stay pale ivory, so do not let the leeks brown. If they start to take on color, lower the heat and add a splash of water.
3. 3Add the potatoes and broth. Peel 3 starchy potatoes (Russet or Yukon Gold) and cut them into small chunks so they cook evenly. Add them to the pot with about 1 litre of chicken broth — enough to cover the vegetables. Bring to a boil, then lower the heat and simmer, partly covered, for 20-25 minutes, until the potatoes are completely tender and pierce easily with a knife.
4. 4Purée until silky. Let the soup cool slightly, then purée it thoroughly with an immersion blender or in a stand blender until completely smooth. For a true restaurant texture, pass the purée through a fine-mesh sieve (chinois) to remove any leek fibers — this is the difference between a home soup and a Ritz-Carlton one. The starch from the potatoes gives a creamy body with no need for flour.
5. 5Stir in the cream and chill. Let the base cool, then stir in 200 ml of heavy cream. Season with salt and white pepper — use white, not black, so there are no dark specks in the pale soup. Cover and refrigerate for at least 4 hours, ideally overnight, until thoroughly cold. To speed it up, set the bowl in an ice bath and stir. The potato starch will thicken the soup as it chills; thin it with cold broth or milk to the consistency you like.
6. 6Season boldly and serve. Taste the cold soup and adjust the salt — cold dulls the palate, so vichyssoise needs more seasoning than it seems when warm; be bolder than you think. Ladle into chilled bowls, scatter chopped chives over the top, and finish with an optional swirl of cream. Serve ice-cold as an elegant summer starter. It keeps 3-4 days in the fridge, covered; do not freeze, as the cream and potato separate into a grainy texture.