Heat the olive oil in a large saucepan and briefly sauté the chopped onion, garlic, ginger, turmeric and cumin. Reduce to medium temperature and add the carrots and sweet potatoes and stir-fry for about 2 minutes. Deglaze with coconut milk and water and let simmer for about 20 minutes, until carrots and sweet potatoes are soft.
Add the lemon juice, then puree the whole thing in a blender or with a hand blender until creamy. Season to taste with salt and freshly ground black pepper. Keep warm with the lid closed.
Mix all ingredients for the harissa oil together until smooth.
Pour the soup into bowls and serve drizzled with the harissa oil.
Wellcuisine-Tipp
If there is any harissa oil left, you can store it in a closed jar in the refrigerator for at least a week.