Ingredients:

  • 1 ½ cups (180 g) All-Purpose Flour
  • 2 Tbsp (25 g) Granulated Sugar
  • ½ tsp (3 g) Fine Sea Salt
  • ½ cup (115 g) Unsalted Butter, chilled and cubed
  • 1 large Egg Yolk
  • 3–4 Tbsp (45–60 ml) Ice Water
  • 1 cup (200 g) Granulated Sugar
  • ⅓ cup (40 g) Cornstarch (Cornflour)
  • ¼ tsp (1.5 g) Fine Sea Salt
  • 1 ½ cups (360 ml) Cold Water
  • 4 large Egg Yolks
  • ½ cup (120 ml) Fresh Lemon Juice
  • 1 Tbsp (5 g) Lemon Zest
  • 2 Tbsp (30 g) Unsalted Butter, chilled and cubed
  • 6 large Egg Whites (room temperature)
  • 1 ½ cups (300 g) Caster Sugar (Superfine Sugar)
  • ½ tsp (3 g) Cream of Tartar
  • ½ tsp (2.5 ml) Pure Vanilla Extract
  • Assorted Gel Food Colouring (Red, Blue, Green, Yellow)

Instructions:

  1. Make the Dough: Pulse flour, sugar, and salt in a food processor. Cut in the cold butter until coarse crumbs form. Add the egg yolk and ice water, mixing just until the dough comes together. Form into a disc, wrap tightly, and chill for at least 30 minutes.
  2. Blind Bake: Preheat oven to 375°F (190°C). Roll out the dough and fit it into the pie dish. Prick the base all over. Line with parchment, fill with pie weights, and bake for 15 minutes. Remove weights and parchment. Bake for another 8-10 minutes until lightly golden. Cool completely on a rack.
  3. Cook Filling Base: In a saucepan, whisk together 1 cup granulated sugar, cornstarch, and salt. Whisk in the cold water until smooth. Heat mixture over medium heat, stirring constantly, bringing to a boil; let it bubble and thicken for 1 minute. Remove from heat immediately.
  4. Temper Yolks: In a separate bowl, whisk the 4 egg yolks vigorously. Slowly drizzle about 1 cup of the hot water mixture into the yolks while constantly whisking. This prevents curdling.
  5. Thicken and Finish Filling: Pour the tempered yolk mixture back into the saucepan with the remaining cornstarch mixture. Cook over low heat, stirring constantly, until the filling thickens to a glossy pudding consistency. Remove from heat. Stir in the lemon juice, lemon zest, and 2 Tbsp butter until melted. Pour the warm filling immediately into the prepared, cooled crust.
  6. Prepare Sugar Syrup (Swiss Meringue): Combine egg whites, caster sugar, and cream of tartar in the metal bowl of a stand mixer. Place the bowl over a saucepan of simmering water (double boiler). Whisk constantly until the mixture reaches 160°F (71°C) and the sugar is completely dissolved (not gritty).
  7. Whip Meringue: Transfer the bowl to the stand mixer. Whisk on medium-high speed until the meringue is glossy, white, and holds stiff, sharp peaks. Add the vanilla extract at the end.
  8. Colour Meringue: Divide the finished meringue into 4 bowls. Gently fold small amounts of Red, Blue, Green, and Yellow gel food colouring into the separate portions.
  9. Assemble Piping Bag and Pipe: Lay out a piece of cling film. Spoon stripes of each coloured meringue side-by-side onto the film. Roll the film into a sausage shape, twist the ends, snip one end, and place this into the piping bag fitted with the star tip. Pipe the rainbow meringue swirls directly onto the warm lemon filling, ensuring coverage edge-to-edge.
  10. Torching and Set: Use a kitchen torch to toast the meringue peaks until they are golden brown and slightly crisp (or use a hot broiler for 1–2 minutes, watching constantly). Allow the pie to cool completely at room temperature, then refrigerate for at least 2 hours to allow the filling to fully set before serving.