3 cups blueberries (fresh or frozen)
2 tsp finely grated lemon zest
1/4 cup lemon juice
1/4 cup chia seeds
Bring blueberries and lemon juice to a simmer in a medium saucepan over medium heat and cook, stirring occasionally, just until blueberries begin to burst. Cover saucepan with the lid for about 5 minutes.
Use a spoon to lightly mash about half of the berries to release their juices. Cook another 5 minutes, stirring occasionally, until juices are reduced by half.
Remove jam from heat and then stir in chia seeds; allow seeds to soak and soften.
Let jam cool slightly, then transfer to heatproof jars or containers. Cover and let cool completely. Chill until ready to use.