01 -
Place blackberries, jalapeno peppers, lemon juice, and sugar into a large saucepan and stir to fully combine the mixture.
02 -
Heat mixture over medium-high heat, stirring occasionally, until berries begin to burst and the sugar is dissolved.
03 -
Using a potato masher or the back of a spoon, press the berries to achieve a smooth consistency.
04 -
Increase heat slightly and cook, stirring every few minutes, until mixture reaches 104°C (220°F), approximately 25–30 minutes.
05 -
Remove from heat and allow to cool slightly before transferring the jam to sterilized jars for storage.