Active Time

　　1 1/2 hr

　　Total Time

　　1 1/2 hr

　　It's hard to believe there's no cream in this soup, it's so velvety. A swirl of minty pistou, added at the last minute, provides complexity.

　　

Ingredients

Makes 8 servings

　　

For squash soup

3/4 stick (6 tablespoons) unsalted butter, cut into pieces

　　1 medium onion, halved lengthwise and thinly sliced crosswise

　　1/2 teaspoon salt

　　2 lb yellow summer squash, halved and thinly sliced

　　2 carrots, thinly sliced

　　1 yellow-fleshed potato (1/2 lb), peeled, halved,

　　4 cups chicken stock or reduced-sodium chicken broth

　　

for pistou

3/4 cup loosely packed fresh mint leaves

　　1/2 cup loosely packed fresh flat-leaf parsley sprigs

　　1 large scallion, chopped (1/2 cup)

　　1/4 cup extra-virgin olive oil

　　2 tablespoons water

　　1/4 teaspoon salt

　　

Make soup:

Step 1

Melt butter in a 6- to 8-quart wide heavy pot over moderate heat, then cook onion with salt, stirring, until softened, about 8 minutes. Add squash, carrots, potato, and stock and bring to a boil. Reduce heat, then simmer, partially covered, until vegetables are very tender, about 20 minutes. Remove from heat and cool soup, uncovered, 10 minutes.

　　

Step 2

Working in batches, purée; soup in a blender until smooth (use caution when blending hot liquids) and transfer to a bowl. Return puré to cleaned pot and thin with water if desired; simmer 3 minutes. Season with salt.

　　

Make pistou while vegetables simmer:

Step 3

Pulse mint, parsley, and scallion in a food processor until finely chopped. With motor running, add oil in a stream, then add water and salt, blending until incorporated.

　　

Step 4

Swirl 1 tablespoon pistou into each bowl of soup.

　　Cooks' notes:

　　•Soup (without pistou) can be made 2 days ahead and cooled, uncovered, then chilled, covered. Reheat before serving, thinning with additional water if desired.

　　•Pistou keeps, its surface covered with plastic wrap, chilled, 3 days. Bring to room temperature before using.