Roll out half of the pastry to fit a 23 cm pie plate. Fit into pie pan and trim p astry 3 cm beyond rim of pie pan. Heat undiluted apple-juice concentrate and cinnamon in a large saucepan. Add the apple slices and cook until partly tend er. Remove apple slices. Mix cornstarch and water until smooth. Add to juice in saucepan and cook, stirring constantly, until thick. Combine apples and sa uce. Cool slightly. Fill unbaked pastry shell and dot top of fruit with marga rine. Roll out remaining pastry and fit over top. Trim pastry 3 cm beyond t he rim of pie pan. Fold edges under and flute. Cut vents in top of pastry. B ake in a preheated 375 degree oven 45 minutes until golden brown.