Wash the apples but do not peel or core them. Cut them in pieces and put into a pan. Just cover the apples with liquid, using 1 pint/500ml water to ¼ pint/125ml white vinegar. Add a large bunch of washed mint and simmer until the fruit is very soft. Strain through a jelly bag and measure the juice. Allow 1lb/450g sugar to each pint/500ml liquid. Stir in the sugar over low heat until dissolved, and then boil hard to setting point. Just before cooking is completed, add some finely chopped fresh mint and a few drops of green food colouring. Skim well, cool slightly and stir well. Pour into small hot jars and cover. Serve with roast lamb.