Method

1. Melt the butter in a large saucepan over a low heat.
2. Add the onion, carrots, garlic, coriander, cumin, smoked paprika, and salt, gently cook for 15 minutes.
3. Pour into the stock and simmer until the carrots are tender, stirring occasionally, about 30 minutes.
4. Blend soup to a puree and serve in bowls with a dollop of sour cream and coriander.