Place the fruits, fresh or frozen, into a saucepan and bring the saucepan to low-medium heat.
Stir and mash fruits with a fork or potato masher to form a fruit mash. If the fruits are frozen, they are difficult to mash straight away, so stir and cook the fruits and mash as soon as they have softened.
Stir in chia seeds or arrowroot flour, bring to a light boil, and stir/cook for 1-2 minutes until the mixture thickens. Remove the saucepan from the heat.
Let the jam cool completely in a glass mason jar for 15 minutes. Then close it with a lid and place it in the fridge to thicken.
