Preheat oven to 375°F (190°C)
Whisk flour and salt in a large bowl
Cut in chilled butter until mixture resembles coarse crumbs
Gradually add ice water one tablespoon at a time until dough just comes together
Form dough into a disc, wrap in plastic, refrigerate at least 30 minutes
Roll out dough on a floured surface to 1/8-inch thickness
Cut out 6 equal circles for 12-cup tartlet shells (for a dozen tartlets)
Press dough into tartlet molds, trim edges with a knife, and flute the edges
Line shells with aluminum foil, add dried beans or weights, and bake until golden (~12-15 minutes)
Remove foil and beans, cool shells completely
Whisk granulated sugar, egg yolks, and softened butter in a saucepan until well combined
Add fresh lemon juice and lemon zest, cook over medium-low heat, stirring constantly, until mixture thickens and coats the back of a spoon (~10 minutes)
Chill lemon curd until it cools completely
Fill tartlet shells with curd and serve chilled