In a small bowl, combine the cornstarch and the 1/3 cup cold water. Stir to combine well, dissolving any lumps.

In a medium saucepan, combine the chopped strawberries, sugar, and salt. Cook over medium heat, bringing the mixture to a gentle boil. Cook until the berries form a sauce, approximately 3 to 5 minutes.

Make sure the cornstarch-water mixture is well blended, then add it to the cooked strawberry sauce. Heat the mixture until the strawberry sauce boils again and thickens and the strawberries are soft. This will take approximately 3 to 4 minutes.

Remove from heat. Stir in the butter and vanilla. Set aside and cool to room temperature.

Beat the heavy cream in a large bowl until it holds its shape in round medium.

Stir the whipped cream into the strawberry sauce and gently fold together to blend evenly.

Spoon the filling into the graham cracker crust and refrigerate for 4 to 6 hours, until firm.

Serve cold with sliced strawberries layered on top of the pie.

Garnish with fresh mint.

Refrigerate any remaining pie for up to 1 day.