Prepare 5 - 6 jars w/ csrewtop: washing, rinsing w/ hot resp. boiling water, drying w/ a fresh tea towel & storing them somewhere near you ready for use.
Wash the plums, remove the pits & quarter each plum. The resulting heap of plums should be 1000 g almost exactly.
Add preserving sugar. The version (2:1) means that you'll need 500 g preservign sugar for 1000 g fruit.
Cut the vanilla pod lengthwise & add to the plum-sugar mess.
Mix thoroughly, add 2 -3 tbsp water & bring to a boil.
Cook at least for the minimum your preserving sugar demands... (about 3 - 5 min ususally!) Better let it cook for about 10 min until the plums start dissolving.
Fill at once into the jars, close the screwtop & put the jars upsite down.