-Place about an inch of water in a saucepan. Place a smaller saucepan over top of the larger one.
-Add the eggs to the smaller saucepan and over medium heat whisk the eggs and the sugar together. Continue whisking and cooking until the mixture thickens slightly.
-Stir in the lemon juice, lemon zest, and butter.
-Cook, whisking frequently, for approximately 20-25 minutes until the mixture becomes thick and creamy.
-Remove from the heat and stir in the vanilla extract and salt.
-Transfer the lemon curd to a bowl and cover with plastic wrap directly on the curd to prevent a skin from forming. Refrigerate for at least one hour (the curd will thicken even more as it cools).
To make the meringue:
-In a large clean bowl of a stand mixer (or a large bowl with a hand mixer), beat the egg whites until frothy. Whip in the cream of tartar and the sugar and beat until the mixture form soft peaks.
To assemble the tartlets:
-Fill each phyllo shell with approximately 2 teaspoons of chilled lemon curd.
-Spoon approximately 2 teaspoons of meringue over the lemon curd.
-Carefully use the chef's torch to flame and brown the meringue on top of each tart lightly.
-Keep the tarts at room temperature (preferred) until ready to serve. *Note - If desired chilled, do not refrigerate for longer than 4 hours before serving. Longer refrigeration of the prepared tarts will make the meringue weep and get soggy.