PASTRY: Place all ingredients, except water, in a bowl and, using a pastry blender or your fingertips, quickly combine until mixture resembles coarse breadcrumbs.
Use a knife to mix in water (as little as possible) until just clumping together. (If using a food processor, process all ingredients except water for about 10 seconds. Add water and process just until clumping together - do not over process).
Tip onto a lightly floured board and press together with your fingers to form a disc. Roll out into a circle and line a 22 cm diameter flan ring or quiche dish. Trim edges and prick base well.
Freeze for 10 minutes, line with foil and bake at 200 ºC for 12 to 15 minutes. Remove foil and continue baking at 180 ºC for 5 to 10 minutes, or until golden brown. At this stage, case can be left overnight.
FILLING: Mix together water, cornflour and castor sugar in a small saucepan.
Bring to boil, stirring continuously with a wooden spoon. Simmer gently, stirring occasionally, for about 10 minutes.
Beat in butter, lemon juice, lemon peel and egg yolks and continue to cook over gentle heat for a few minutes, or until thick and smooth and egg yolks no longer taste raw. Do not allow to boil.
Tip into a bowl, cover closely with clingwrap or waxed paper to prevent a skin forming and leave to cool. At this stage, filling can be refrigerated overnight.
MERINGUE: Whisk egg whites in a medium (preferably metal) bowl until stiff. Still whisking, add sugar (a spoonful at a time) and continue to whisk until very stiff and shiny.
Tip filling into pastry case and spread out evenly. Pile meringue on top, covering filling completely.
Bake at 180 ºC for about 15 minutes (if eating immediately), or at 150 ºC for 25 to 30 minutes (if not eating immediately). This makes a firmer meringue, but filling will warm and soften so it needs to cool again before cutting).
TOTAL KILOJOULE COUNT: 11 515 kJ (2 750 Cal). A portion: 1 440 kJ (345 Cal).