Prepare all your vegetables.
In a pot over medium heat, melt butter.
Then add your onion, garlic, cumin, coriander and cook until fragrant. About 2 minutes
Then add your carrots, sweet potato, stock pot, then pour in the water. Stirring until the stock has dissolved.
Leave to boil until the carrots are fork tender or for 20-25minutes.
Add soup to a blender or food processor and blend until smooth.
Add chopped coriander to the blender and blend until the leaves have broken up.
Transfer soup back to the pot and on low heat, add yoghurt, chilli flakes and season with salt and pepper.
Stir until the soup has become smoother. Simmer for 5 minutes, stirring occasionally.
Divide soup into bowl, soup some of the yoghurt on top, garnish with some chilli flakes, coriander and serve with toasted sourdough bread.