In a large bowl, combine half of the strawberries and lemon juice; mash berries. Add 1/3 cup plus 2 tablespoons sugar; set aside. In a large bowl, combine the cream cheese, lemon zest and remaining sugar until smooth. Spread into the crust.
In a large saucepan, combine cornstarch and reserved strawberry mixture until blended. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in food coloring if desired. Cool slightly.
Fold in blueberries and remaining strawberries. Spread over cream cheese mixture. Cover and refrigerate for at least 3 hours.