Peel the apples and onions and chop them into small cubes. Pluck the thyme from the stalks, put in a saucepan with the apples, onions, cinnamon stick, balsamic vinegar and the preserving sugar, stir and stir for 30 minutes. leave.
Bring to the boil while stirring, let simmer for about 4 minutes. Remove the cinnamon stick and pour into prepared twist-off glasses.