1. Peel the sweet potatoes and cut them in big pieces.
2. Peel the yellow onion and cut it in thin slices.
3. Fry the onion in a big pot with 2 table spoons of Huile de Tous les Jours olive oil until it becomes golden.
4. Add the sweet potatoes and let them cook for 2-3 minutes.
5. You can now add 90 cl of boiling water and let it all simmer for 20-25 until the sweet potatoes become soft.
6. Cut the fire, drain your mixture of sweet potatoes and onion.
7. Using a handheld blender, mix your preparation until it gets the consistency of a thick soup.
8. Add to it the fresh cream and sweetened chestnut purée. Mix it well.
9. Season with a little pinch of Camargue fleur de sel salt and one more generous of black Phu Quoc pepper.
10. Pour your soup in soup plates and decorate each of them with a drizzle of White balsamic vinegar with white truffle and a drizzle of white truffle olive oil, as well as a pinch of summer truffle salt.