Instructions

• Whisk together juice, zest, sugar, and eggs in a 2-quart heavy saucepan. Stir in butter and cook over moderately low heat, whisking frequently, until curd is thick enough to hold marks of whisk and first bubble appears on surface, about 6 minutes. It will thicken more as it chills.
• Transfer curd to a bowl and chill, its surface covered with plastic wrap, until cold, at least 1 hour.