Step 1

Rinse the blackberries, then add them to a large pan together with the sugar and the lemon juice.

Step 2

Leave to simmer on a low to medium heat until the liquid released is nearly absorbed, and the jam is thick enough to be poured into jars, depending on the heat that could take up to 2 hours.

Step 3

The jam will thicken further when it cools down.

Step 4

Rinse the jars, and place them in the oven at 180 degrees Celsius (350 Fahrenheit) for 10 minutes to sterilise.

Step 5

Pour the hot jam into the hot jars, making sure you do not fill the jars to the brim, but there is about half an inch of headspace.

Step 6

Tighten the lids well, then place the jars upside down and leave to cool completely.

Step 7

If the fourth jar is not quite full, it can be stored in the fridge and consumed within 3-4 weeks.

Step 8

Otherwise, the jars can be stored in a cool place, and the jam should last for 1-2 years.