Clean the cauliflower, wash it and cut it into very small florets. Peel onion and garlic, dice finely. 3⁄4 Fry cauliflower, onion and garlic in hot oil. Add 1 l water, broth and lemon juice, bring to the boil.
Simmer for about 10 minutes.
Dice bread. Heat the herb butter and roast the bread all around in it. Puree the soup. Add remaining florets and crème fraîche, bring to the boil and cook for about 5 minutes. Season with salt, pepper and 1 pinch of sugar, sprinkle with the croutons.