I'm not a fan of buttermilk, au natural. But use it in a cold summer vegetable soup recipe, and nothing could be better.

I add spinach to make it green, and the tarragon adds a note of subtle sophistication.

Zucchini that are the size of baseball bats lose their flavor and can often be bitter; reserve these specimens for your next game.

Yield 6-7 cups
Active Time: 20 minutes
Chill Time: 2-24 hours

Ingredients

2 tablespoons extra-virgin olive oil

2 leeks, white and light green parts only, washed thoroughly, then thinly sliced

5 medium-sized zucchini, washed, halved lengthwise, then cut crosswise into 1/8-inch-thick slices( 5 cups)

Zest and juice from 1/2 lemon

3 1/2 cups chicken or vegetable stock

1 cup loosely packed fresh spinach

1 tablespoon finely chopped fresh tarragon

3/4 cup well-shaken buttermilk

Directions

1. In a medium-sized saucepan, heat oil to medium heat. Sauté leeks with a pinch of salt, stirring occasionally, until softened, about 6 minutes.

2. Add zucchini, lemon zest and juice, and simmer, stirring occasionally, about 5 minutes or until zucchini is softened. Add stock and simmer an additional 6-8 minutes, stirring in spinach the last couple of minutes.

3. Purée zucchini mixture and tarragon in a food processor or with an immersion blender until smooth (use caution when blending hot liquids). 

4. Stir in buttermilk and season to taste with kosher salt and freshly ground pepper.

5. Refrigerate at least 2-3 hours before serving, and preferably overnight.