Melt the butter in a large saucepan. Add the onion and fry gently until soft and golden (this should take about 10 minutes). Add the garlic and coriander.
Peel and finely slice the carrots and potatoes and stir them into the mixture. Cut three strips of orange zest from the orange with a sharp knife and add to the pan along with the squeezed orange juice made up to 300ml with shop-bought orange juice or fresh if available.
Add the chopped carrots and potatoes and stir in the stock and simmer for about 20-30 minutes until the vegetables are tender
Remove the orange peel. Puree the soup in a blender until very smooth. Add salt and pepper as required. Place in a jug, cover, and if possible leave overnight for the flavours to develop.
Return the soup to the pan and reheat until piping hot.
Either stir in the cream and fresh herbs, bring back to nearly boiling and serve in a large tureen garnished with croutons. Or serve the soup in individual bowls with a swirl of cream and fresh herbs sprinkled on top of each and pass a bowl of croutons separately and/or crusty brown rolls.
Visit our Soup and stew recipes section for more delicious meal ideas.