Cold Cucumber Soup with Tarragon

6 pounds cucumbers (about 6 cucumbers), peeled, seeded, and coarsely chopped (12 cups)
4 green onions, chopped
1 jalapeno pepper, stemmed, seeded, and minced
2 tablespoons finely chopped fresh tarragon leaves
1 tablespoon finely chopped fresh mint leaves
1 tablespoon finely chopped fresh chervil
2 garlic cloves, mashed to a paste with 1 teaspoon salt
1-1/2 teaspoons salt
1/2 teaspoon cayenne pepper
3 cups plain yogurt
3 cups sour cream, divided
3 tablespoons extra-virgin olive oil
2 teaspoons white wine vinegar
1 teaspoon lime juice
2 tablespoons minced fresh chives

Combine the cucumbers, green onions, jalapenos, tarragon, mint, chervil, garlic, salt, cayenne, yogurt, 2 cups sour cream, olive oil, white wine vinegar, and lime juice in a large bowl. Working in batches, puree the ingredients in a blender until very smooth. Transfer the soup to the refrigerator until well chilled, at least 2 hours. Taste and adjust the seasoning, if necessary. Serve the soup, with each bowl garnished with a dollop of the remaining sour cream and some of the minced chives.

Yield: 2 quarts, 4 to 6 servings