First sterilize the jars.
Peel kiwi and apple, remove the core of the apple and cut everything into small pieces.

Put the fruit in a pan, add sugar and lemon juice and start cooking, stirring often.
After about 1 hour blend with the blender and, if you want, add a pinch of green food coloring.

Evaluate the consistency by making the saucer test (put a few drops of jam on a dry and clean plate and then tilt it: if the jam slips quickly, it must cook again, if it is slow, it is ready).
Once ready, fill the jars with the jam still warm, close well with the lids and turn them upside down, letting them cool in this way.

The kiwi jam is ready, you can eat it right away or keep it in the pantry, in the dark, for a few months. Once the jar is open, store it in the fridge and consume it within a couple of weeks at the most.