1. Combine the lemon juice, rind, water and sugar.
2. Heat, stirring till the sugar is dissolved.
3. Stir in the dissolved corn flour and egg yolks, and continue cooking till the mixture is thick (about 5 minutes).
4. Remove the pan from the heat and leave to stand for a few minutes..
5. Spoon into the pastry case.
6. Beat the egg whites till stiff. Gradually beat in the sugar. The mixture should form stiff, dry peaks.
7. Pile the meringue on top of the lemon filling, taking care to cover it completely.
8. Bake at 150ºC for 20 - 25 minutes, or until the meringue has set and is golden brown.
9. Leave to stand till cool.