Wash the mirabelle plums, cut in half and remove the stone.
Measure and mix the water and apple juice. Add the cornstarch while stirring so that no small lumps form. Then add the sugar and stir again until you can no longer hear the sugar crunch. Put the mixture in a saucepan and bring to the boil. Add mirabelle plums and bring to the boil again and, depending on the ripeness of the fruit, simmer on a very low level for about 5. Do not cook too long, otherwise they will overcook!
Place a sieve over a bowl and pour the contents of the pot into the sieve. Divide the mirabelle plums from the sieve into 3 dessert bowls.
Put the juice back in the saucepan. Add the cinnamon and vanilla sugar. Possibly add a shot of multi-fruit juice and bring to the boil again. Let cool down briefly and then spread over the mirabelle plums.