Cooked kiwifruit can have a metallic taste, removing the seeds fixes the problem.
Halve kiwifruit lengthwise, with a sharp spoon scoop out the seedy pulp and discard. Scoop out the remaining pulp until you have 1 lb. Mash the pulp in a big heat-proof jug, add the lemon juice and microwave until it boils vigorously (5 minutes).
Stir in the sugar until it is mostly dissolved. Cook on a low power setting for about 8 minutes until a little jam sets. Add a little green food colouring to enhance the appearance.
Gold kiwifruit makes a beautiful golden jam without added colour.