Add strawberries to a saucepan over medium-high heat and cook until the berries start to break down and the mixture is bubbling. You can use the back of a spoon or potato masher to mash the berries and create your desired consistency.
Stir in the chia seeds and lemon juice. Then taste, and add sweetener if desired. If your berries are sweet you might not need to add any sweetener at all.
Remove mixture from heat and let cool the mixture cool and thicken, about 5 to 10 minutes.
You can use right away or let cool completely before transferring to sealed container and placing in chia jam in your refrigerator. The jam will keep for up to 1 week.
Notes
I like my jam with texture from the fruit, but if you like your jam to have a smooth consistency, you can blend the mixture in a high-powered blender or use an immersion blender to blend until smooth.