2 pounds asparagus, tips reserved, stalks cut into 1-inch lengths
2 tablespoons unsalted butter
3 medium leeks, white and tender green parts only, thinly sliced
1/2 pound Yukon Gold potatoes, peeled and cut into 1-inch chunks
2 1/2 cups chicken stock or canned low-sodium broth
2 cups water
1 large thyme sprig
1 1/2 cups milk
1 1/4 teaspoons salt
1/4 teaspoon freshly ground white pepper
Chive Oil, for serving
In a saucepan of boiling salted water, blanch the asparagus tips until crisp-tender, about 1 minute. Drain the asparagus tips in a colander and refresh under cold water. Pat dry, halve the tips lengthwise and set aside.
Melt the butter in a large saucepan.Add the leeks and cook over moderate heat, stirring, until softened, about 5 minutes. Add the asparagus stalks, potatoes, stock, water and thyme and bring to a boil. Reduce the heat to low, cover and simmer until the potatoes are tender, about 15 minutes.
Discard the thyme sprig. Working in batches, puree the soup in a blender, then transfer to a large bowl. Stir in the milk, salt and white pepper. Let the soup cool to room temperature, then refrigerate until chilled, at least 4 hours or overnight.
Ladle the soup into chilled bowls and drizzle with Chive Oil. Garnish with the asparagus tips and serve.
The soup can be refrigerated for 2 days.
A crisp, herbal Sauvignon Blanc with sassy fruit will complement the vegetables and spices in the soup and the salads that follow; try one from California.