Top with a waxed disc and seal with a lid, then leave to cool. Spoon into warm, freshly sterilised jars, to within 3mm from the top.
Use potato masher and mash fruit till soft and additional liquid forms. Bring to a boil, then down to a rolling simmer for 5 minutes. Return the saucer to the freezer for a minute to cool the jam, then push it with the tip of your finger – if the jam wrinkles on the surface, the setting point has been reached. In a medium sauce pot, add strawberries, maple syrup and chia seeds. To test whether the setting point has been reached, take the pan off the heat and either use a sugar thermometer (once it gets to 105☌ it’s ready) or spoon a little of the jam onto a cold saucer from the freezer.Cook slowly over a low heat until the sugar has dissolved, then bring to the boil and bubble rapidly for about 20 minutes or until the setting point is reached (see next step). Put a couple of saucers in the freezer (unless you have a sugar thermometer).
Add the rest of the sugar and the lemon juice. Transfer to a preserving pan or very large high-sided saucepan, scraping out the bowl thoroughly.Leave them to macerate for a couple of hours.
Tumble into a large bowl and stir through half the sugar, coating the fruit well. Wipe the strawberries with a damp cloth to remove any dirt.