Chop the strawberries and place them in a saucepan together with the water.

Bring to the boil (lid on), then turn down the heat medium and let it bubble away for 15 minutes. Add the lemon juice if you want to store the jam for longer than 1 week - it prevents the growth of bacteria.

Mash the strawberries with a potato masher (or with a fork), then continue to cook on low-medium for another 30 minutes until reduced by half. You want it to bubble peacefully. Bubbles will become smaller as the liquid evaporates. Stir regularly with a spatula to prevent the jam from burning. Towards the end of cooking, stir constantly.

Taste. If necessary, sweeten with 1 tbsp of powdered sweetener.

Add the ground chia seeds and stir. Cool and fill into a sterilised jar. Store in the fridge.