Steps
- Pulse 175g of all-purpose flour, 100g of cold cubed butter, 1 tablespoon of icing sugar, 1 egg yolk, and 1 tablespoon of cold water just until dough forms. Roll to line a 9 × 1in / 23 × 2.5cm tart pan; prick and chill for 30-60 minutes.
- Preheat the oven to 400°F / 200°C with a baking sheet inside. Line the shell with foil and weights; bake for 15 minutes, remove both, and bake for 5-8 minutes, until pale gold. Reduce to 350°F / 180°C.
- Meanwhile, mix 2 tablespoons of cornstarch, 100g of golden superfine sugar, and the zest of 2 large lemons in a saucepan. Stir in 125ml of lemon juice.
- Add 200ml of orange juice diluted with water: for each 200ml, use the juice of a small orange and top up with water. Stir over medium heat until thick and bubbling.
- Off the heat, beat in 85g of butter. Beat together 3 egg yolks and 1 egg, then stir into the filling. Cook over medium heat, stirring vigorously, until thick; remove from the heat.
- Whisk 4 room-temperature egg whites to soft peaks. Gradually whisk in half of 200g of golden superfine sugar, then 2 teaspoons of cornstarch, then the remaining sugar, until thick and glossy.
- Reheat the filling and pour into the shell. Spread meringue over the hot filling from the edges inward, touching the crust all around. Bake for 18-20 minutes, until lightly colored.
- Cool in the pan for 30 minutes, then unmold and cool for 30-60 minutes before slicing.