Add the mulberries, lemon juice and sweetener to a medium saucepan.
Bring to a gentle simmer over medium heat. Cook for 10 to 15 minutes, stirring often and mashing the berries as they soften.
Remove the pan from the heat and stir in the chia seeds.
Let the jam stand for 10 minutes. It will continue to thicken as it cools.
Taste and adjust the lemon or sweetener if needed. Transfer to a clean jar, cool and refrigerate.
Notes
Storage: This is a refrigerator/freezer jam and is not safe for water-bath canning. Refrigerate for up to 1 week or freeze in a freezer-safe container for up to 3 months, leaving headspace for expansion.Mulberries contain naturally occurring sugar even though this recipe has no added sugar.