(click on the text to highlight each stage):

1. Place the apple juice and vinegar in a preserving pan or large saucepan (the liquid should not come more than halfway up the pan). Bring to the boil then remove from the heat.
2. Whisk in the pectin then stir in the sugar (or stir in 1kg Jam Sugar). Heat gently stirring continuously, until the sugar and pectin have dissolved. Do not allow to boil.
3. Add the knob of butter, then still stirring, increase the heat and bring to a full rolling boil, one that bubbles vigorously, rises in the pan and cannot be stirred down. As soon as this stage is reached, start timing.
4. Boil for 4 minutes only. Remove from the heat and stir in the mint. Allow to cool for about 10 minutes, stirring occasionally, until the mint no longer floats on the surface. Pot and cover in the usual way.
5. Variations 1. Apple and Rosemary Jelly - Replace the mint with 30ml (2 level tbsp) finely chopped fresh rosemary. 2. Cider and Herb Jelly - Replace the apple juice with 600ml (1pint) strong dry cider, and replace the mint with 30ml (2 level tbsp) chopped thyme.