Roll half of pastry to 1/8-inch thickness on a lightly floured surface; fit into a 9-inch pie plate. Set aside.
Combine sugar, raisins, flour, salt, and water in a medium saucepan; stir well. Bring to a boil; cook 1 minute, stirring constantly. Remove from heat, and cool 5 minutes.
Gradually stir about one-fourth hot mixture into egg; add to remaining hot mixture, stirring constantly. Pour raisin mixture into top of a double boiler; place over boiling water, and cook 5 minutes, stirring frequently. Remove from heat, and stir in lemon rind and juice. Cool completely. Pour cooled raisin mixture into pastry shell.
Roll remaining pastry to 1/8- inch thickness; cut into 3/4-inchwide strip's, and arrange in a lattice fashion over filling. Trim edges; seal and flute. Bake at 450° for 10 minutes. Reduce heat to 350°, and bake an additional 20 minutes.