Ingredients:

  • 4 Tablespoons unsalted butter
  • 3 large leeks, white and light green parts only, thoroughly washed and sliced
  • 1 medium yellow onion, diced
  • 5 pounds (680g) Russet or Idaho potatoes, peeled and roughly chopped
  • 1 teaspoon kosher salt
  • 1/2 teaspoon freshly ground black pepper
  • 6 cups (1.4 Litres) low-sodium chicken or vegetable stock
  • 1/2 cup (120 ml) heavy cream
  • Extra salt and pepper, to taste
  • Fresh chives or parsley, for garnish (optional)

Instructions:

  1. Clean the Leeks: Slice the leeks lengthwise, fan the layers, and rinse thoroughly under cold running water to remove all grit and dirt. This step is crucial for smooth soup.
  2. Melt the Butter: In a large Dutch oven or heavy-bottomed pot, melt the butter over medium-low heat. The goal is to sweat the vegetables, not brown them.
  3. Sauté Aromatics: Add the prepared leeks, diced onion, 1 teaspoon of salt, and pepper to the pot. Cook, stirring frequently, for 8 to 10 minutes until the leeks are tender and translucent, ensuring they develop no color whatsoever.
  4. Simmer: Add the chopped potatoes and pour in the stock. Bring the mixture to a rapid boil, then immediately reduce the heat to low, cover partially, and simmer gently for 25 to 30 minutes, or until the potatoes are fork-tender.
  5. Blend the Soup: Remove the pot from the heat. Use an immersion blender to carefully blend the soup in the pot until it is completely smooth and velvety. If using a standard blender, work in small batches, venting the lid to allow steam to escape.
  6. Finish and Season: Return the blended soup to the pot (if necessary). Stir in the heavy cream. Taste and adjust seasoning with extra salt and pepper as needed. If serving as Vichyssoise, chill completely before serving.
  7. Serve: Serve piping hot, garnished with fresh chives or parsley, and optional croutons or bacon.