Potato Leek Soup Recipe

Prepare aromatics

In a heavy-bottomed pot or Dutch oven over medium heat, melt the unsalted butter. Add the sliced leeks and diced onion and sweat gently for 8–10 minutes, stirring occasionally, until softened and translucent but not browned. Add the minced garlic and cook 30–45 seconds until fragrant.

Add potatoes and stock

Add the diced potatoes to the pot and stir to coat with the butter and aromatics. Pour in the chicken or vegetable stock to cover the vegetables (about 6 cups). Add the bay leaf and thyme sprigs. Increase heat to bring to a gentle boil, then reduce to a simmer.

Simmer

Simmer uncovered for 15–20 minutes, or until the potatoes are very tender and easily pierced with a fork. Taste the broth and add 1 to 1 1/2 teaspoons sea salt and 3/4 teaspoon ground black pepper, adjusting to taste.

Finish with cream and milk

Remove and discard the bay leaf and thyme stems. Stir in the heavy cream and milk, then heat gently for 3–4 minutes—do not boil. Use an immersion blender to purée the soup until smooth and silky. Alternatively, carefully transfer the soup in batches to a blender and purée, then return to the pot.

Adjust seasoning & texture

If the soup is too thick, thin with a little additional warm stock or milk (1/4 cup at a time) to reach the desired consistency. Reheat gently and adjust seasoning with salt and pepper if needed. Keep warm on the lowest heat setting while you prepare croutons and crème fraîche.

While the soup simmers, combine the crème fraîche, finely snipped chives, grated or finely chopped black truffle (reserve thin slices for finishing), lemon juice, 1/4 teaspoon sea salt, and a pinch (about 1/8 tsp) of freshly ground black pepper in a small bowl. Stir until smooth. Taste and adjust salt or lemon to brighten. Chill briefly if you prefer a cooler garnish; otherwise keep at room temperature.

Make croutons

Preheat the oven to 375°F (190°C). Toss the bread cubes with the olive oil and 1/2 teaspoon kosher salt on a baking sheet in a single layer. Bake for 10–12 minutes, stirring once halfway through, until golden and crisp. Remove and let cool slightly.

Assemble and finish

Ladle the hot potato leek soup into warmed bowls. Dot each bowl with a generous spoonful (about 1 tablespoon) of the chive crème fraîche and use the back of the spoon to swirl slightly. Scatter a small handful (about 2 tablespoons) of croutons over each bowl. Sprinkle the reserved fresh chive snips and finish with thin shavings of black truffle. If desired, drizzle up to 1 tsp of truffle oil per bowl for extra aroma. Serve immediately.