In a medium saucepan, combine the chopped strawberries, granulated sugar, water, and lemon juice. Cook over medium heat, stirring occasionally until the strawberries begin to release their juices and the mixture starts to simmer (about 5 minutes).

In a small bowl, mix the cornstarch with a couple of tablespoons of water to create a slurry. This will help to thicken the filling.

Slowly add the cornstarch slurry to the simmering strawberry mixture while stirring constantly. Continue to cook for an additional 3-5 minutes until the mixture thickens and becomes glossy.

Remove from heat and stir in the vanilla extract. If you prefer a smoother filling, you can use a fine mesh strainer to remove any larger strawberry pieces.

Allow the filling to cool to room temperature before using. Once cooled, it can be used immediately or stored in a sealed container in the refrigerator for up to one week.

For a more intense strawberry flavor, you can blend the filling until smooth after cooking.

This filling is perfect for cakes, cupcakes, and pastries.