In a food processor, pulse all-purpose flour and powdered sugar until well combined. Add cold unsalted butter and blend until the mixture resembles coarse crumbs.

Incorporate the egg yolk and cold water, pulsing until a dough forms. Chill the dough for 30 minutes.

Preheat the oven to 350°F (175°C). Roll out the dough and press it into mini tart pans, pricking the bases to prevent bubbling. Line with parchment and bake for 10-12 minutes until golden. Allow to cool completely.

In a saucepan, combine fresh lemon juice, lemon zest, granulated sugar, and eggs. Whisk together and cook over medium heat, stirring constantly until the mixture thickens after 8-10 minutes.

Remove from heat and whisk in unsalted butter until completely smooth. Pour the lemon curd into the cooled tart shells and refrigerate for 1 hour to set.

Set a heatproof bowl over simmering water. Whisk together egg whites, granulated sugar, and cream of tartar until warm and the sugar dissolves.

Remove from heat and beat with an electric mixer until stiff peaks form, about 5-7 minutes. Stir in vanilla extract and violet food coloring.

Pipe the meringue onto the chilled tarts, creating height and swirls.

Use a kitchen torch to lightly toast the tips of the meringue until golden brown. Garnish with edible lilac petals or dried lavender.