Place fruit in small saucepan. Cook on medium-low heat, stirring often, until it starts to release juice.
Turn the heat to medium and using a spatula or a whisk, press the fruit down to break it down. Stir often. Cook until mixture looks like sauce. You can leave it chunky or break the fruit down more.
Remove saucepan from heat. Add lemon juice. Stir well.
Add chia seeds and stir well.
As the jam sits and cools, it will thicken up. Pour into a jar with lid.
Notes
Store in the fridge for up to 2 weeks. If using fresh strawberries: wash and hull them, then chop them into smaller pieces. You can add pure vanilla extract and honey if desired. Taste the jam once cooled and adjust to your liking.
If you do not like a chunky texture in your jam, you can place the mixture in a blender or use an immersion blender and blend until smooth.