Wash the strawberries very well, and remove the green top stems.
Weight the cleaned strawberries and adjust the sugar quantity accordingly.
Add the sugar over the strawberries and let them macerate for a good 5 to 6 hours. Or even better, overnight.
Make sure to cover the pot with a cloth, to avoid fruit flies.
Once the strawberries are floating in their own juice and the sugar dissolves, they are ready.
Add the lemon juice over the strawberries, and mix well.
Put the strawberries in a large pot, three times their volume. This is because the liquid will rise a lot.
Turn the heat on medium, and start boiling the strawberries, mixing from time to time with a wooden spoon.
Make sure the clean all the foam that forms at the surface – this is all the impurities from the sugar.
From start to finish, you will need to boil the pot for around 20 minutes. You will know when it’s ready because the colour of the strawberries will turn a beautiful, deep red.
To test if the jam is ready, pour a tablespoon on a small plate. If you can run your finger through it and leave a clean mark, it’s ready.
Turn the heat off and let the jam rest for 10 minutes.
Meanwhile, sterilise the jars.
Wash the jars and their lids very well, with soap and water. Rinse well to remove all the dish soap.
Put the clean jars and lids in the oven on a metal tray and turn the heat on to 150 degrees Celsius.
Let them dry in the oven for 10 minutes.
Take them out carefully, as they will be hot.
To prevent cracking, make sure the jars are on a metal surface, such as the tray or stainless steel knives.
Pour the jam in each jar up to the top line, and close the lid.
Place the jars upside down and leave them to cool down slowly.
Once they are cold, place them in your pantry for winter.