Wash and prepare the fruit. If using berries, remove stems and rinse thoroughly. For larger fruits like peaches or plums, peel if desired and chop into small pieces.

Place the fruit in a medium saucepan over medium heat. Use a potato masher to break down the fruit slightly.

Add the sugar and lemon juice. Stir to combine, and bring the mixture to a simmer.

Stir frequently as the fruit releases its juices, mashing larger pieces until smoother, or leave chunky for texture.

Continue simmering for 20 to 30 minutes, stirring often, until the mixture thickens slightly. Test by placing a small spoonful on a chilled plate; if it holds its shape when you run your finger through it, it is ready.

Remove from heat and let cool for 10 minutes.

Ladle the jam into sterilized jars. Allow to cool to room temperature before sealing and refrigerating.