Remove the stalks, wash the fruit and put into a large saucepan with the water.
Bring to the boil and simmer gently stirring occasionally, to prevent sticking, until the fruit breaks down and the skins are soft. Fresh fruit can take up to 1/2 hour to soften, frozen fruit may only take 10 minutes, make sure all of the added water is evaporated off.
Add the Sure-Set and heat stirring until it is dissolved, then bring to the boil and boil vigorously for 4 minutes. (See 'Adding Sure-Set' for details on boiling and timing).
Pot and cover in the usual way; label and date. (See 'Potting and covering' for details).