50mlsherry plus more to tastealternatively white wine or, for a non-alcoholic version, 1 tbsp lemon juice
1.2lhot water
1tspsalt plus more to taste
For the lemon and thyme crumble:
1tbspolive oil
1tspfresh thyme leaves
1pinchsalt
Freshly ground black pepper
1/2Grated zest of of organic lemon
Instructions
Heat the olive oil in a large saucepan. Sweat the onion and garlic in it. Set aside 10 of the chestnuts. Put the rest together with the potatoes and fry briefly while stirring. Deglaze with sherry or white wine. Add water and salt and simmer over medium heat for about 20 minutes until the potatoes are tender. Puree in a blender until creamy. If the soup is too thick, add a little more water. Season to taste with salt, sherry and freshly ground black pepper.
For the crumble, dice the chestnuts that were set aside. Heat the olive oil in a small pan. Fry the chestnuts in it until browned. Then add the thyme, fry briefly and remove from the heat. Salt and pepper lightly and stir in the lemon zest.
Pour the soup into bowls, arrange with the crumble and a small dash of olive oil and serve.