Both watercress and sherry vinegar will refresh your palate. This delicious cold watercress soup is wonderful in the summer.

Cook the soup: Melt the butter in a heavy-bottomed saucepan. Add the onions, garlic, and leeks and toss to coat. Sweat vegetables on low heat for 8 minutes. Next, add cut potatoes and stock. Sprinkle with salt and freshly ground pepper. Cover with a lid and cook over medium heat for 20 minutes. Add the chopped watercress and cook uncovered for approximately 5 minutes or until soft. Do not overcook, otherwise the soup will lose its delightful green color and turn khaki.

Finish the soup: Puré the soup in a blender or food processor. Add cream, season to taste, let cool a little, then refrigerate.

Just before serving, add the sherry red wine vinegar, mix the sour cream and milk until smooth, and store in a squeezable bottle. Serve in soup bowls and garnish with whole watercress leaves, sour cream, and freshly ground pepper.

Presentation suggestions: A teaspoon of sour cream and some freshly ground pepper will add class to this refreshing soup. Or, try serving in martini glasses outside on the patio for an elegant presentation.