Peel and chop the onions. Peel and wash carrots and cut them into large slices. Potatoes peel, wash and roughly dice.
Heat clarified butter in a pot and fry onions until translucent. Add potatoes and carrots, fry while turning. Season with 1 tsp. sugar, salt and pepper.
Pour in broth and juice, bring to the boil, cover and simmer for about 20 minutes. Clean and wash spring onions and cut into fine rings. Puree the soup finely and season to taste. Serve with crème fraîche and spring onions.
Garnish with basil leaves.