Sauté the trimmed and chopped fennel and leek with 1 tablespoon of butter to soften - about 5 minutes

Add 2 1/2 cups stock; boil, cover, lower the heat and simmer until fennel is tender - about 15 minutes

Cool slightly and purée

I used a vitamin to purée which produces a beautiful creamy soup but depending on your type of blender you may need to strain the mixture at this point

Refrigerate

When cool, garnish with tarragon and serve