1. Melt the butter, add carrots, peeled and finely chopped.
2. Fry for 5 mins, taking care not to burn the carrots.
3. Add 6 cups chicken stock, salt and pepper.
4. Simmer until the carrots are tender. Cool and liquidize (or sieve).
5. Add cream. Adjust seasoning (salt, pepper and mustard to taste). Chill.
6. Serve the soup very cold in chilled bowls.
7. Float a sprig of mint leaves in each bowl.

Note: For a vegetarian version, use a vegetable stock.