Roughly chop the apples, there is no need to core or peel them, and heat these in a pan along with the mint leaves (roughly chopped) and enough water just to cover and no more.
Simmer for approximately 20 minutes until apples are pulpy.
Remove from heat and carefully pour this mixture into a jelly bag suspended over a large bowl (see my resources page on jelly making for more information).
Leave to drip over night and DO NOT squeeze the bag.
Boil the apple juice in a heavy based pan until it has thickened and reduced down to a quarter of its original volume.
Add the strained fruit juice to the pan and the white wine vinegar.
Bring to the boil and bubble for approximately 5 minutes until the setting point has been reached.
Allow to cool for 5 minutes before adding the extra chopped mint leaves and spoon into sterilised jars.