01 - Set the oven temperature to 350°F (175°C).
02 - Mix flour, sugar, and salt. Incorporate cold butter by rubbing with fingers or pastry cutter until coarse crumbs form.
03 - Add egg yolk and 1 tablespoon cold water, combining just until dough forms. Add a second tablespoon of water if necessary.
04 - Shape dough into a disk, wrap with plastic, and refrigerate for 20 minutes.
05 - Roll out dough to 1/8-inch thickness on a floured surface. Cut into circles approximately 3 inches in diameter. Fit circles into tartlet pans, pressing edges, then prick bottoms with a fork.
06 - Line shells with parchment and fill with baking weights or dried beans. Bake for 12 minutes, remove weights and parchment, then continue baking 8 to 10 minutes until golden. Cool completely.
07 - Whisk eggs and sugar until smooth. Stir in lemon juice and zest.
08 - Place bowl over simmering water and cook, stirring constantly until thickened and coating the back of a spoon, about 10 minutes.
09 - Remove from heat and whisk in cubed butter until well blended and glossy.
10 - Pour lemon curd into cooled tartlet shells and refrigerate for at least 1 hour to set.
11 - Decorate with fresh berries, powdered sugar, or mint leaves as desired. Serve chilled.