Place the frozen fruit in a medium saucepan. Heat it over medium heat for 3 minutes, covered. Then remove the cover and continue to cook over medium heat for another 2 to 3 minutes (or until all the fruit is defrosted), stirring occasionally. Remove the fruit from the stove and let it cool for a minute.

Coursely mash the fruit with a fork or a masher, then add the lemon juice, maple syrup, and chia seeds to the fruit mixture. Stir to combine evenly. Divide the mixture between 2 one-cup jam jars and refrigerate for up to two weeks. Alternately, you can freeze the extra jam for longer storage.