Cook the fruit. In a large sauce pan, combine the strawberries, rhubarb and water. Cook over medium heat until the fruit is soft, about 5-10 minutes. Mash the fruit with the back of a spoon until you reach your desired texture of jam. Stir in 1-2 tablespoons of sweetener, according to how sweet your fruit is.
Grind the chia. While the fruit is softening, grind the chia seeds in a small blender or coffee grinder until fine.
Thicken your jam. Stir the ground chia seeds into the softened fruit. Cook over low heat for another 5 minutes. The jam will continue to thicken as it cools. Transfer to a jar or resealable containe and store in the fridge.
Your chia jam will keep in the fridge for 1-2 weeks, or freeze for later!