This is a small tribute to "Maman Blanc" – and to "Papa Blanc" too as most of the vegetables would come from his garden. The choice of vegetables and herbs is completely yours. Chervil is one of my favourite herbs – it is very popular in French cuisine yet little used here. You can blend the soup if you like and a spoon of crème fraîche is always welcome.
- On a medium heat, sweat the onion, garlic, carrots, celery and leeks in the butter for 5 minutes (don’t let it colour) to extract maximum flavour. Season with salt and freshly ground white pepper.
- Bring the water to a boil and add it to the vegetables (this reduces the cooking time and keeps the colours lively).
- Add the courgette and tomato and fast boil for a further 5 minutes. Freshness is the key to success. It’s crucial not to let it cook for longer.
- Whisk in the butter (or sour cream or both!) and add the chervil. Taste and correct the seasoning if required. Pour into a large tureen and serve.
Other variations: omit the sour cream and chervil and add pesto for a delicious pistou soup. Cooking the soup with a teaspoon of green curry paste, coconut milk, lemon grass, lime leaves, chilli and galangal would produce a delicious soup with flavours from Thailand.