If using fresh rhubarb, wash trim, and weigh (if using frozen, just weigh). Then cut into very small pieces, no more than 0.5 cm (above 1/4 inch) and place in a large saucepan.
Add the lemon or orange juice if being used, then add the Sure-Set and heat while stirring to dissolved, bring to the boil and boil vigorously for 4 minutes. (See 'Adding Sure-Set' for details on boiling and timing).
N.B. If lemon or orange juice is not being used, add the Sure-Set to the cut up rhubarb and allow to stand until some of the juice is extracted, before heating and boiling for 4 minutes. Pot and cover in the usual way; label and date. (See 'Potting and covering' for details).
Note: If you prefer a more traditional softer fruit jam see method for Rhubarb and Ginger jam and omit ginger if you wish.