In a food processor, combine flour and powdered sugar, pulsing until well mixed. Add cold butter, pulsing until the mixture resembles coarse crumbs. Incorporate the egg yolk and ice-cold water, pulsing until the dough forms. Chill the dough for 30 minutes, then preheat your oven to 350°F (175°C). Roll out the dough and press it evenly into mini tart pans, baking for 10–12 minutes until golden. Let the tart shells cool completely on a wire rack.

In a medium saucepan, whisk together freshly squeezed lemon juice, zest, sugar, and eggs. Cook the mixture over medium heat, stirring constantly for about 8–10 minutes, or until it thickens and coats the back of a spoon. Remove from heat and stir in unsalted butter until melted and smooth. Allow the curd to cool slightly before filling the cooled tart shells. Chill the tarts in the refrigerator for at least 1 hour to allow the curd to set.

In a heatproof bowl, whisk together egg whites, sugar, and cream of tartar. Place the bowl over simmering water, gently mixing until the mixture is warm and the sugar has dissolved. Remove from heat and beat with an electric mixer for about 5–7 minutes, or until stiff peaks form. Gently fold in vanilla extract and violet food coloring to create a beautiful lilac hue. Pipe the meringue onto the cooled tart shells, creating swirls or peaks for a lovely finish.

Using a kitchen torch, lightly toast the tips of the lilac meringue until they turn a golden brown, being careful not to burn. For an elegant touch, garnish your Mini Lemon Tarts with edible lilac petals or a sprinkle of dried lavender. Serve immediately, or refrigerate until ready to delight your guests with this beautiful spring dessert.