Preparation Method
- Fill a medium saucepan with about 1 inch ofwater and bring to a simmer.
- Meanwhile, whisk together the eggs, egg yolks,and sugar in a medium heat-safe bowl until smooth and pale yellow. Add the lemon zest and juice and the salt. Place the bowl over the simmering water, making sure the bottom of the bowl does not touch the water. Use a wooden spoon to constantly stir the lemon mixture, scraping down the sides of the bowl often, until the curd begins to thicken and it reaches 165°F to 170°F on an instant-read thermometer, 8 to 12 minutes.
- Remove the bowl from the saucepan and set on top of a folded kitchen towel. Add the butter 1 tablespoon at a time, and whisk until incorpo-rated. Set the bowl over the simmering water again and continue to whisk until the curd is thick enough to coat the back of a spoon and it reaches 175°F to 180°F. The whisk’s tines should leave a trail that quickly disappears in the bottom of the pan. (If you overcook the curd, the whisk will leave a wide trail that does not fill in quickly.) Stir in the vanilla extract (if using).
- For the ultimate in smoothness, pour the warmcurd through a fine-mesh sieve set over a bowl. Place a piece of plastic wrap directly on the curd’s surface to prevent a skin from forming on the top. Refrigerate until chilled, at least 2 hours and up to 1 week.
Pro Tip
If you don’t have a zester, you can peel the lemon zest off in strips and pulse it with the sugar in a mini food processor or spice grinder.
