This piquant tart cradles sections of fresh tangerine and a hint of zest.
Prepare an ice bath, and set aside. In a medium heat-proof bowl, whisk together eggs, yolks, and 1/4 cup sugar; set aside.
Place lemon juice, tangerine juice, two-thirds of zest, and remaining 1/4 cup sugar in a small, heavy-bottomed, nonreactive saucepan. Bring to a boil.
Pour the boiling liquid over the egg mixture, whisking constantly. Return the mixture to the saucepan, and bring to a boil again, whisking constantly. As soon as the curd starts to boil, 1 to 2 minutes, remove saucepan from the heat.
Transfer curd to a fine sieve set over a medium bowl. Using the back of a ladle, push the curd through the sieve; discard the solids. Gradually whisk in the butter until incorporated. Set the bowl over ice bath, stirring occasionally.
Once completely cool, lay plastic wrap directly on surface of curd to prevent a skin from forming. Chill until firm, about 3 hours.
Heat oven to 375 degrees. Have ready 48 2 1/4-inch fluted tartlet pans. (Alternatively, use 24 pans, and bake 12 shells at a time.) On a lightly floured surface, roll out each disk of dough to an 1/8-inch thickness. Using a 3-inch round cutter, cut out 24 circles. Press a circle into each pan, and place a second pan on top; press the 2 pans together lightly. Chill shells until firm, about 30 minutes.
Bake shells until edges begin to take on color, about 12 minutes. Remove top pans, and continue baking until pastry dries out completely and becomes golden brown, 12 to 14 minutes more. Transfer shells to a wire rack to cool completely.
To serve, place about 1 tablespoon curd in each shell. Top each with 2 tangerine sections, and sprinkle with the remaining zest.
The curd (steps one through five) and the tartlet shells (steps six and seven) both can be made up to three days before you assemble the dessert.