Cut the rhubarb into small pieces (do not peel) and place in a saucepan. Add the water and bring to the boil. Mix the pudding powder as instructed and use it to thicken the fruit. Season to taste with vanilla sugar and sugar.
For the semolina dumplings, bring the milk, butter and sugar to the boil. In the meantime, beat the egg. Then add the semolina to the boiling milk and finally add the beaten egg.
Shape the dumplings with two teaspoons and add to the finished fruit soup.