In a mixing bowl, combine all-purpose flour, powdered sugar, and a pinch of salt. Cut in the chilled butter using a pastry cutter until the mixture resembles coarse crumbs. Roll out the dough to about 1/4 inch thick, then cut out circles for mini tart pans. Chill in the fridge for at least 30 minutes.

Preheat the oven to 350°F (175°C). Prick each tart shell's base with a fork to prevent bubbling. Bake for 12-15 minutes until lightly golden. Let cool completely.

In a medium saucepan, whisk together fresh lemon juice, granulated sugar, eggs, lemon zest, and vanilla extract over medium heat. Stir constantly for 7-10 minutes until thickened. Cool slightly before pouring into tart shells.

Beat egg whites with an electric mixer until soft peaks form. Gradually add sugar while continuing to beat until stiff peaks form. Add lilac food coloring if desired and fold in gently.

Pipe the lilac meringue onto each filled tart creating peaks. Use a broiler or kitchen torch to toast the meringue tops until lightly golden, about 1-2 minutes.

Garnish with fresh mint leaves and serve immediately for best texture.