01 - In a food processor, pulse together flour, powdered sugar, and salt until combined.
02 - Add cold cubed butter to flour mixture and pulse until the consistency resembles coarse crumbs.
03 - Add egg yolk and 1 tablespoon ice water, then pulse until dough just comes together. Add additional ice water one teaspoon at a time if needed.
04 - Transfer dough to a lightly floured surface, gather into a disk, wrap in plastic wrap, and refrigerate for 30 minutes.
05 - Preheat oven to 350°F (175°C). Roll out chilled dough to 1/8-inch (3 mm) thickness.
06 - Cut dough into circles approximately 3 inches (8 cm) in diameter. Press into mini tartlet pans and trim excess dough.
07 - Prick shell bottoms with a fork, line with parchment paper, and fill with baking weights or dried beans.
08 - Bake for 12 minutes, then remove weights and parchment. Continue baking 5-8 minutes until golden brown. Cool completely.
09 - In a heatproof bowl, whisk together lemon juice, lemon zest, granulated sugar, and eggs until thoroughly combined.
10 - Set bowl over a saucepan of simmering water, whisking constantly until mixture thickens, approximately 8-10 minutes.
11 - Remove from heat and whisk in butter pieces until the mixture is smooth and creamy.
12 - Pass the lemon curd through a fine-mesh sieve into a clean bowl. Cover surface with plastic wrap and refrigerate for at least 1 hour until set.
13 - Spoon or pipe the chilled lemon curd into cooled tartlet shells, distributing evenly.
14 - Arrange assorted fresh berries over the lemon curd filling.
15 - Dust lightly with powdered sugar and garnish with fresh mint leaves if desired. Serve chilled.