Herbed Courgette Soup - good hot or cold

I've lifted this recipe pretty much exactly as it's written on the My Gourmet Connection Web site. The version below is merely my personal preference for the options provided in the original. It makes for a tasty soup to bring on a picnic since it's as good hot as it is, cold.

¼ cup (2oz/58gr) butter
1 cup onion, chopped
4 to 5 cloves garlic, minced
¼ cup flour
3½ cups chicken broth (veg stock for Vegetarian)

1½ lbs unpeeled any kind of summer squash - a mix of colours is nice
½ cup cream
1½ Tbsps lemon juice
1½ to 3 Tbsps chopped fresh tarragon OR 1 Tbsp dry
Salt and freshly ground black pepper

Note: Choose small to medium squash with tender skins and leave them unpeeled for both extra colour and nutritional value.

1. Cut the squash into small (½") cubes and set aside.
2. Melt the butter in a large saucepan over medium heat. Add the onion and sauté until soft and translucent, 3 to 5 minutes. Add the garlic and cook until fragrant, 1 minute longer.
3. Add the flour to combine and, stirring continuously, cook until the flour is pale golden in colour, 3 to 4 minutes. 
4. Slowly whisk in the chicken broth and continue whisking until the mixture is smooth and well blended.
5. Add the squash and season with salt and pepper. (If using dry tarragon, add now and mix in). Cover and continue cooking, stirring occasionally, until the squash is tender, 12 to 15 minutes.
6. Remove the soup from the heat and purée until smooth. Return the pot to the stove, stir in the cream and lemon juice and heat through, 1 to 2 minutes.
7. Taste and adjust the seasoning, add the tarragon, ladle into serving bowls and top with a dollop of sour cream if desired.
8. OR allow to cool completely and serve with freshly chopped tarragon sprinkled on top.