Blackberry jam

Put a saucer in the fridge for later. Put the blackberries, sugar and lemon into a heavy-based pan or jam pan, and warm over a medium heat. Stir a few times until the blackberries start to release their juices and the sugar has dissolved.

Turn up the heat to high and cook for 10-15 minutes on a rolling boil, stirring every so often, until the liquid reduces to a thin syrup. Place a teaspoon of the jam onto the cold plate and leave to cool for 30 seconds. Press your fingertip through the jam, and if the top of the jam has formed a skin and wrinkles up, the jam has reached setting stage. Keep boiling for 5 minutes if the jam remains syrupy and runs on the plate during this test, then try again.

Skim any scum from the top of the jam using a large spoon. Remove from the heat and leave for 15 minutes before decanting into warm sterilised jars (this helps thicken the jam slightly and stops all the fruit sinking to the bottom of the jars).

The jam will keep for six months in a cool dark place. Once opened, chill, and use within four weeks.