Sift flour, confectioners' sugar, and salt together in a bowl. Press softened butter into flour mixture and combine until blended. Pat stiff dough into two 9x13-inch pans forming even layers. Pierce through dough with a fork every 1/2-inch in lines parallel to the long sides of the pans; use a clean yard stick laid across the pan as a guide to make straight rows. Chill dough until firm.

Preheat the oven to 350 degrees F (175 degrees C).

Bake in the preheated oven until lightly golden, about 11 minutes. Cut into rows using fork marks, again using a yardstick as a pan guide. Cut rows into 3-inch lengths to make fingers. Cool completely in the pan.

Meanwhile, beat eggs in a bowl. Stir in sugar, lemon juice, melted butter, and lemon rind. Pour into the top of a double boiler set over simmering water; cook and stir until thick and smooth, 5 to 10 minutes. Cool at room temperature.

Serve shortbread fingers with lemon curd.