Bring the lemon mixture to the boil and cook on a gentle heat for about one hour (keep the lid on) until tender.
In a large jam pan add the diced courgette along with two tablespoons of the lemon liquid and cook on a low to medium heat until translucent and all the courgette juices have disappeared - about 20 to 30 minutes.
Turn the heat down to the lowest setting and add the jam sugar and stir until dissolved.
Attach the jam thermometer (if using) to the side of your pan and add the lemon mix and grated ginger and stir.
Increase the heat and when the mixture reaches a full boil, boil rapidly for 8 to 10 minutes until setting point is reached.
Setting point is reached when the jam thermometer reaches 104℃ or 220F.Alternatively, use the wrinkle test: Remove your pan from the heat and test for setting point by dropping a little jam onto a cold saucer, return to the fridge and leave to cool for a minute. Push the jam gently with your fingertip, if the jam crinkles, setting point has been reached. If not, reboil for a couple of minutes and repeat until setting point is reached.
Leave to cool for about 10 minutes before pouring into warm, sterilised jars.
Seal the jars as quickly as possible and wipe the jars with a warm damp cloth.
Label when cold with Courgette and Ginger Jam and the date.