Put lemon pie
filling in medium saucepan. Stir in sugar and 1/4 cup (60ml) water. Blend
in egg yolks thoroughly. Stir in 1 3/4 cups (425ml) water, lemon rind and
prunes. Set over moderate heat and cook until mixture comes to a full boil
and thickens, stirring constantly. Turn down heat and continue cooking 3
minutes more, stirring constantly. Cool. Fold in sour cream. Spoon mixture
into cooled pie shell and chill well.