Gently wash the strawberries in water with a dash of vinegar.
Drain the fruit and pat dry on a kitchen towel.
Remove the pedicels and cut into quarters.
Cook the pie filling
Combine the quartered strawberries, sugar, salt, lemon juice and 120 ml (half cup) of water in a pan.
Place the pan over a medium heat and cook for 5 minutes until the strawberries soften.
Combine the remaining cold water with corn starch in a small bowl.Gently stir the corn starch, a small quantity at the time, into the strawberry mix and bring to the boil to thicken the sauce.
Adjust the sweetness and acidity if necessary. Transfer the sauce in a jar, seal and wait until cool.