Puree 1 pint of the largest berries. Strain and set aside.
In saucepan, stir together the sugar and cornstarch. Stir in the lemon juice, mixing so there are no lumps. Gradually add strawberry puree. Cook over medium heat, stirring constantly, until just reaching a boil. Simmer slowly for 1 minute, stirring constantly.
Mix the puree with the strawberries and spoon into prepared pie shell. Chill until firm, about 1 hour.