Step 1

Put the grated courgettes, ginger, lemon zest and juice in a large heavy-based pan or preserving pan. Place over a low heat for 4–5 minutes, stirring to prevent the mixture from sticking while the juices draw out.

Step 2

Add the sugar, a third at a time, stirring until it has completely dissolved. Turn up the heat to a steady boil for 7–8 minutes until the mixture is glossy and clear; it will thicken and the boil will be slower. Using jam sugar should ensure the jam will set.

Step 3

Remove from the heat and gently stir (in one direction only) to disperse any foam, adding a drop or two of oil if it doesn’t disperse.

Step 4

Tip the jam into a wide-necked jug with a good pouring lip, then fill the warm sterilised jars to the brim and immediately seal with screwtop lids.

Step 5

Store in a cool, dark, dry place for up to a year. Once opened keep in the fridge and use within 6 weeks.