Make the curd according to the recipe using the optional gelatin. Set aside while making the crust. (The curd should be slightly warm when poured into the tart shell.)
Preheat the oven to 350 °F. Roll the short dough to fit into a 12" fluted tart pan. Prick the bottom of the dough all over and blind bake until golden brown.
Remove the pan from the oven and pour the still warm curd into the tart shell. Allow the shell and curd to cool to room temperature. Refrigerate the tart for several hours or overnight until the filling is set.
Combine 2 oz water and 6 oz (3/4 cup) granulated sugar in a small saucepan. Cook the sugar syrup on medium high heat, stirring until the sugar is melted. Once the syrup begins to boil do not stir the syrup. Allow it to cook to 240°F (soft ball stage).
While the syrup is boiling, whip 4 large egg whites on medium speed. When the whites are soft peak reduce the mixer to medium low and slowly add the ½ teaspoon vanilla extract and remaining 2 oz (1/4 cup) dry sugar. Increase the speed to medium high and whip to full peak.
As soon as the syrup is at the correct temperature, remove the pan from the heat. With the mixer running on medium low, slowly pour the hot syrup between the edge of the bowl and the whisk to avoid splattering the syrup. Increase the speed to medium high and continue whisking until the whites are cooled.
Preheat the broiler in the oven. Spread or pipe the meringue onto the curd. Put the tart under the broiler to brown the top of the meringue. If you have a propane torch you can use that to brown the meringue instead of broiling.
The assembled tart will keep in the refrigerator for several days but is best the day it's made.