Review of basic techniques

1. Remove the zest from the grapefruit.
2. Halve the grapefruit and squeeze out the juice. Save the pulp. Cut the peel in half.
3. Squeeze all the other fruit; reserve and strain the juice.
4. Weigh the apple and grapefruit juice - weigh out an equal amount of sugar.
5. Tie all the seeds in a piece of cheesecloth.
6. Pour the juices, peels, seeds and sugar into a pot.
7. Let the sugar dissolve over low heat, then turn up the heat and boil for 25 minutes, stirring often.
8. Check the cooking stage by placing some of the mixture onto a cold plate.
9. Remove the seeds and peels and pack the jam into jars.