My Favorite Lemon Pudding
Whisk the sugar and the cornstarch together in a medium saucepan. Add the milk and whisk until smooth. Add the egg yolks, zest, and salt and cook, stirring frequently at first and constantly towards the end, over medium heat until thickened enough to thickly coat the back of a spoon.
Let cool to room temperature. Chill, loosely covered, for at least 2 hours and up to 3 days, or until set and thoroughly chilled. Serve chilled.