You can prepare the lemon curd in advance, since it has to cool completely before baking the tart.
Mix the lemon zest, salt and sugar in a bowl and knead with your fingers until the sugar has a yellowish tone. Then add the eggs and beat until the eggs and sugar are well combined. Add the lemon juice and mix. Transfer the mixture to a small metal saucepan and heat over medium heat, and stir constantly. Once the mixture has a thick consistency similar to béchamel sauce or has reached 75ºC, remove from the heat and add the butter in small pieces, one at a time. Once everything is incorporated, add the vanilla. Now let the curd cool completely, transfer it to a container or a bowl, and cover the curd with plastic wrap, let the plastic touch the cream directly to prevent the top from drying out.