It's a very tart lime base with just a little meringue around the edge to provide a little sweetness.
When browning the meringue, I realised that I really need a kitchen blowtorch to be able to do these things well as the heat from the grill made my lovely, smooth lime curd surface blister. So that has been added to the birthday wish-list!
115g salted butter, cut into pieces
180ml freshly-squeezed lime juice (from about 5-6 limes)
zest of two limes
pinch of salt
3 large egg yolks
3 large eggs
For the meringue -
2 large egg whites
pinch of salt
a few drops vanilla essence
You also need one pre-baked Sweet Tart Crust
Preheat the oven to 180C.
In a medium-sized saucepan, warm the butter, lime juice, sugar, zest, and salt.
In a jug, whisk together the eggs and the yolks.
When the butter has just melted and the mixture is warm, gradually pour some of the lime juice mixture into the eggs, whisking constantly. Scrape the warmed eggs back into the saucepan and cook the mixture over low heat.
Stir the mixture constantly over low heat, using a whisk, until the filling thickens and coats the back of a spoon. Do not let it boil. It will take at least 30 mins at a low temperature to thicken sufficiently.
Bake for 10 minutes until set and then remove and cool slightly.
Now make the meringue. Whip the whites on high speed in a mixer to soft peaks. Next, gradually add the sugar and the salt, while whipping on high speed, until the meringue is shiny and stiff. Beat in the vanilla last.Scrape the meringue into a pastry bag fitted with a star tip and pipe a ring around the edge of the tart.
Pop the tart under the grill (or, as I would recommend, use a blowtorch on the meringue), watching carefully, as it will brown quickly.
When the meringue begins to darken, remove the tart from the oven and cool completely before slicing.