Add the cumin and coriander, stir to coat the vegetables and allow a minute or two to cook. Add the orange juice and stock and bring to a simmer. Simmer until a knife can easily pierce the carrots - about 15 -20 minutes.
Remove from the heat and allow to cool slightly, then use an immersion blender (or transfer the soup to a blender) and blend until it is smooth (or chunky!) enough for your taste. Return the soup to the heat.
In a small bowl, whisk the sour cream to loosen it a little, then add a ladeful of hot soup to the cream and mix well - this will stop the sour cream curdling when you add it to the hot soup. Stir the cream mixture back into the soup and mix well.
Check for seasoning and add salt and pepper as necessary. Add a squeeze of lemon juice and bring the soup bring back to a simmer before serving, taking care not to boil it as the cream can separate.
Ladle the hot soup into bowls and serve topped with a swirl of sour cream and a dusting of cumin.
Recipe by Cooksister | Food, Travel, Photography at https://www.cooksister.com/2014/01/carrot-cumin-soup-66-square-feet-recipe-book-giveaway.html