Thaw berries until most of free ice has disappeared. Drain off the juice; measure and stir it into mixture of sugar, tapioca and cornstarch in saucepan. Heat rapidly until thickening is complete. Boiling is not necessary. Set aside to cool.
Add berries and lemon juice to cooled, thickened juice. Pour filling into pastry-lined 9" pie pan. Cut vents in top crust; c