Scald the tomatoes, peel, chop, transfer to a pan and combine with the preserving sugar. Cut open the vanilla pod, scoop out the seeds, add and bring to the boil. Add the rosemary and lemon juice and cook over a medium heat for 3-4 minutes. Remove the vanilla pod and rosemary. Pour the jam, while still boiling hot, into clean, warmed jars and seal immediately. Briefly upend the jars with screw-top lids and leave to cool completely.
Serve the jam with the Manchego.