Curd requires full attention. Undercooked, it will be runny. Overcooked, it will overthicken and clump. Cook in a heavy-bottomed pan using a whisk to sweep up curd from sides and corners. At the exact moment it boils, remove the curd from the heat and pass through a fine-mesh strainer. This curd is specifically for the Lemon Meringue Tarts.
- 1 cup granulated sugar
- Finely grated zest of 1 lemon
- 1⁄2 cup freshly squeezed lemon juice
- 4 large eggs plus 1 large egg yolk
- 1 1⁄2 sticks (6 oz.) unsalted butter, cut into 1-inch pieces
- In a medium bowl, rub together the sugar and lemon zest with the palms of your hands until fragrant. Set aside.
- Using a fine-mesh strainer, strain the lemon juice into a medium nonreactive saucepan. Set the strainer in a medium heatproof bowl next to the stove.
- In the saucepan, add the eggs, egg yolk, and sugar mixture, and whisk to combine. Add the butter, and set the pan over medium heat. Cook, whisking constantly all over the bottom of the pan and into the edges, until the butter is melted and the mixture is thickened slightly, 3–5 minutes. At the very first sign of a boil, quickly remove the pot from the heat and strain the lemon mixture into the prepared bowl.