1 Tablespoon plus 2 teaspoons finely grated lemon zest
1 cup fresh lemon juice
1 1/3 cups sugar
4 large eggs
pinch of salt
14 tablespoons (1 3/4 sticks) unsalted butter, cut into tablespoons
Whisk together lemon zest, lemon juice, sugar, eggs, and salt in a heavy medium-sized saucepan. Cook, stirring, over moderately low heat until mixture warms, then add butter and cook, whisking constantly, until curd is thick enough to hold the marks of the whisk and first bubbles appear on surface, about 10 minutes.
Immediately pour curd through a fine mesh strainer set over a bowl, stirring with a wooden spoon to help force it through. Discard what is left in strainer. Cool to room temperature, stirring occasionally, then refrigerate, covered, until cold.
from the Gourmet Cookbook by Ruth Reichl.