Start by making the passion fruit curd. Combine the egg yolks, passion fruit puree, sugar, and cornstarch in a small pot. Cook, constantly stirring until the curd thickens. This takes approximately 10 minutes. The curd is done cooking when it has thickened enough to coat the back of a spoon and holds its shape when you run your finger through it. It should have a smooth and creamy consistency.
Pour the curd into a bowl and mix in the melted coconut oil. Wrap the bowl in plastic wrap (the plastic wrap should rest directly on top of the curd) and refrigerate for at least an hour.
When the curd is ready, divide it among the tart shells. You can do this with a spoon or a piping bag if you want it to be very neat.
Next, make the meringue. Place the egg white and sugar in a bowl and set it over a pot of simmering water (double boiler.) stir until the sugar has dissolved completely in the egg whites. To know if the sugar has dissolved, you can take a small quantity of the mixture and rub with your fingers. If you feel sugar granules, keep going. If it’s completely smooth, the sugar has dissolved.
Remove the bowl and pour into a stand mixer. Whip until stiff peaks form.
Pipe the meringue topping on top of the tarts and toast with a blow torch if desired.
