Wash the cauliflower florets, and braise them in melted butter, covered, in a larger pot, together with two handfuls of rice, until tender, about 15-18 minutes.
Sprinkle with the flour, mix in, then pour in the broth, and bring to a boil.
Meanwhile make the dumplings: beat the egg with a pinch of salt, pinch small dumplings off it with a spoon into boiling salted water, and cook for 2 minutes, then drain.
When serving, mix in the egg, the butter and the sour cream.
Add the dumplings cooked in salted water to the soup, and serve hot.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.