In a mixing bowl, combine all-purpose flour, powdered sugar, and salt until well mixed. Cut in chilled unsalted butter until the mixture resembles coarse crumbs. Roll out the dough on a floured surface and cut into circles. Chill for 30 minutes.

Prick the bases with a fork to prevent puffing during baking.

In a saucepan, whisk together fresh lemon juice, granulated sugar, eggs, lemon zest, and vanilla extract. Heat over medium-low heat, stirring constantly, until thickened.

Remove from heat and cool slightly before pouring into chilled tart shells.

Beat egg whites on medium speed until soft peaks form, then gradually add sugar and beat on high until stiff peaks form.

Gently fold in lilac food coloring if desired.

Pipe the lilac meringue onto the cooled lemon curd in each tart shell, creating beautiful swirls.

Optionally, toast the meringue lightly with a kitchen torch until golden brown.

Garnish with fresh mint leaves and arrange on a platter for presentation. Serve chilled.