Classic Potato Leek Soup
Leeks sweated slowly until sweet and silky, simmered with Yukon Gold potatoes in good stock, then blended until impossibly smooth. One of the most elegant soups in the French repertoire — and one of the simplest to make. Serve hot in winter or ice cold as vichyssoise in summer.
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Potato leek soup is all about patience in the first step. The leeks must be sweated — cooked gently in butter over low heat — until completely soft, sweet, and limp, without taking on any color. This takes 12–15 minutes. Rushing by using higher heat browns the leeks and introduces a slightly bitter, caramelized note. Low and slow produces a soup with a clean, delicate, sweet leek flavor.
Use Yukon Gold potatoes, not russets. Their slightly waxy texture and higher fat content produce a creamier, smoother puree without the glue-like texture that over-blended russets can create. Blend until just smooth, then stop — over-working potato-based soups develops starch into a gummy texture.
Ingredients
- 4 large leeks, white and light green parts, cleaned and sliced into rounds
- 600g (1.3 lbs) Yukon Gold potatoes, peeled and cubed
- 3 tbsp unsalted butter
- 1 tbsp olive oil
- 3 garlic cloves, sliced
- 1 L (4 cups) good quality chicken or vegetable stock
- 1 bay leaf
- 120ml (½ cup) heavy cream
- Salt and white pepper
- Fresh chives, finely sliced, to garnish
- Good-quality extra-virgin olive oil, to finish
Instructions
- Clean the leeks. Slice leeks and soak in a large bowl of cold water, swishing to dislodge grit. Lift clean leeks out, leaving grit behind. Pat dry.
- Sweat the leeks. Melt butter with olive oil in a large pot over medium-low heat. Add leeks, garlic, and a generous pinch of salt. Cook slowly, stirring every few minutes, for 12–15 minutes until completely soft and bright green. No browning — this step defines the flavor.
- Add potatoes and stock. Add diced potatoes and bay leaf. Pour in stock. Bring to a simmer. Cook 20 minutes until potatoes are completely tender and break apart easily with a fork.
- Blend. Remove bay leaf. Blend until completely smooth using an immersion blender or in batches in a blender. Don't over-blend.
- Season and finish. Return to pot. Stir in cream. Season generously with salt and white pepper (white pepper keeps the soup visually clean and pale). Heat gently — do not boil after adding cream.
- Serve. Ladle into warm bowls. Swirl a little cream on top. Garnish with chives and a drizzle of good olive oil. Serve with crusty sourdough.
Chef's Pro Tips
- White pepper is traditional in this soup — it keeps the bowl pale and visually elegant. Black pepper works but adds specks.
- For vichyssoise: cool the blended soup completely, refrigerate until cold, then stir in cream cold. Adjust seasoning — cold dulls flavor, so be more assertive with salt.
- Save the dark green leek tops for making stock — they add flavor and shouldn't be wasted.
- Add a rind of Parmesan to the simmering soup for extra depth — remove before blending.