Cucumber Dill Soup

3 English (hothouse) cucumbers, peeled, halved lengthwise, and seeded1 cup Greek-style or other thick, whole-milk plain yogurt1 tablespoon fresh lemon juice3 green onions, including tender green tops, chopped3 tablespoons chopped fresh dill1 clove garlic, chopped1 teaspoon caraway seeds, crushed1 teaspoon kosher salt 1/4 teaspoon ground white pepper1 cup vegetable stock or reduced-sodium vegetable broth2 tablespoons fruity extra-virgin olive oilCoarsely chop 5 of the cucumber halves and transfer to a large bowl. Add the yogurt, lemon juice, green onions, dill, garlic, caraway seeds, salt and white pepper. Stir to combine, cover with plastic wrap, and set aside at room temperature for 1 hour to blend the flavors.Dice the remaining cucumber half and set aside until ready to serve.In a blender, purée the cucumber mixture until smooth. With the machine running, slowly add the stock and purée until it is fully incorporated, about 30 seconds. Transfer to a pitcher, cover with plastic wrap, and refrigerate until chilled, about 2 hours. (The soup can be prepared up to 12 hours in advance and stored in an airtight container in the refrigerator. If it separates, simply stir it until emulsified.)Just before serving, stir in the diced cucumber and olive oil. Pour the soup into wide-mouthed glasses or cups and serve at once.Serves six.Cook's notes: For foolproof transport, select a container with a tight-fitting lid that permits easy pouring. Pour in the soup, cap tightly, place upright in an ice chest, and secure in place with bags of ice or cool packs. To serve, pour the soup into wide-mouthed glasses or cups so that guests can sip it.Nutrition values per serving: 96 calories, 7 g fat (1 g saturated), 7 g carbohydrates, 3 g fiber, 3 g protein, 5 mg cholesterol, 450 mg sodium."Williams-Sonoma Outdoor Entertaining" (2006 Weldon Owens Inc., $24.95)