Warm the 2 tablespoons of olive oil in a heavy, nonreactive 6-quart saucepan. Add the leeks, asparagus, peas, sorrell and 2 teaspoons salt and cook until warmed through. Add 1 cup of the water, cover and sweat the vegetables over moderate heat until the water has evaporated, about 10 minutes. Add the remaining 7 cups of water and bring to a boil. Reduce the heat and simmer for 5 minutes. Increase the heat to high and add the spinach and watercress. Cook, stirring to submerge the leaves, until wilted, about 2 minutes. Transfer the soup to a bowl set in a larger gowl of ice. Stir the soup frequently to chill it quickly and thoroughly. Once it is completely cold, pour the soup into a blender and puree until smooth Season with salt and pepper. To serve, gently reheat the soup. Spoon it into warmed soup plates or bowls. Garnish each serving wiht 1 tablespoon of the ricotta and a drizzle of extra-virgin oilive oil and serve. Per serving: 92 Calories; 6g Fat (52% calories from fat); 5g Protein; 7g Carbohydrate; 8mg Cholesterol; 58mg Sodium Recipe by: Food and Wine, April 1996