Wash the strawberries and drain the water. Hull the fruits and cut them up as you wish.
In a saucepan, add the strawberries, sugar and lemon juice and let simmer over very low heat.
Mix cornstarch with water and add the mixture into the simmering fruits mix.
Let the fruits soften and simmer in the sugar syrup until the sugar is completely dissolved and the fruits start to soften.
Continue to simmer over low heat, stirring often until the mixture thickens.
Remove the strawberry filling off the heat and let it cool to room temperature before storing it in a clean jar or container.
Keep the fruit filling refrigerated until it is ready to be used.
This amount makes about 200 grams of filling.