Chilled Green Soup with Olives

This is a delicious summer soup, but the colour deteriorates after a day so make only as much as you need. To keep the colour vivid the herbs are blended in oil before being exposed to the acidic citrus juice. This seals in their aroma and taste and protects the green colour against the acidity, which has to fight through a barrier of oil. It may sound a bit scientific, but it does help the soup!