01 -
Whisk flour, powdered sugar, and salt in a bowl. Cut in the cold butter until the mixture looks like coarse crumbs. Stir in the egg yolk and 1 tablespoon cold water, adding a little more water only if the dough feels dry.
02 -
Gather the dough into a disk and chill for 20 minutes. Roll thinly, cut small rounds, and press them into a mini muffin pan or tartlet pan. Prick the bottoms with a fork and chill for 10 minutes.
03 -
Heat the oven to 350 F. Bake the shells for 12-15 minutes, until lightly golden at the edges and dry in the centers. Cool completely in the pan, then lift out carefully.
04 -
Whisk eggs, yolks, sugar, lemon juice, zest, butter, and salt in a heatproof bowl set over gently simmering water. Cook, stirring often, for 8-10 minutes until thick enough to coat a spoon.
05 -
Strain the warm curd through a fine sieve into a clean bowl. Press plastic wrap against the surface and chill until cold and spoonable, at least 1 hour.
06 -
Spoon lemon curd into the cooled shells. Top each tart with berries and mint if using. Dust lightly with powdered sugar just before serving, if desired.