Peel and finely dice the onion, then sauté in 50 g butter. Add flour and stir until smooth. Pour white wine, broth and 150 g cream on top. Let everything cook for about 3 minutes while stirring. Add crème fraîche and season the soup with salt, pepper and a pinch of sugar.
Wash the wild garlic, pat dry and cut finely. Add to the soup. Then puree the soup with the mixer.
Debark the toast, cut into cubes and toast in the remaining butter until golden brown.
Shortly before serving, whisk the egg yolks with the rest of the cream, slowly pour into the soup and whisk with the blender. Add the lemon peel and season to taste. Don`t cook anymore!
Pour the soup into plates and serve with toasted bread cubes.