Combine sugar and quartered strawberries in a bowl. Allow to macerate for about 20 minutes at room temperature or until you have ¾ cup strawberry juice and the sugar completely dissolves. Strain the liquid from the strawberries into a measuring cup and add water as needed, about ¼ cup, until you reach 1 cup of liquid. Set the strawberries aside.

Whisk 3 tablespoons of cornstarch into the liquid and transfer to a small pot with about ¼ cup of the strawberries. Use a potato masher or spatula to break the strawberries into small pieces. Heat the mixture over medium-high heat and stir constantly for about 8-10 minutes until it thickens to a jam-like consistency.

Pour the thickened strawberry sauce over the remaining strawberries and toss to combine. Then transfer the mixture into your prepared pie crust and flatten the berries with a spatula. Refrigerate your pie for at least 4 hours or until completely set.