4lemons, zested and juiced (to make 1/3 cup juice)
1stickbutter (113g), diced
Instructions
Add enough water to a medium saucepan to come about 1-2 inches up the side. Bring to a simmer over medium-high heat.
Meanwhile, combine egg yolks, sugar and salt in a medium size bowl and whisk until smooth (about a minute). Add juice and zest to egg mixture and whisk until smooth.
Once water reaches a simmer, reduce heat to medium-low and place bowl on top of saucepan (bowl should be large enough to fit on top of the saucepan without touching the water). Whisk until the mixture is thickened to the point that, when you hold the whisk above the mixture, the curd should fall into a ribbon shape and briefly hold its shape on top of the mixture before disappearing. Depending on the stove, this will take about 15-20 minutes (if you find that it’s not thickening at all, you may want to edge up the heat a little, but go easy!). If using a thermometer, the mixture should reach 170°F or 76°C.
Remove from heat and stir in butter, a piece at a time, allowing each addition to melt before adding the next. Pour the mixture into a clean container, cover by laying a layer of plastic wrap directly on the surface of the curd, and refrigerate. The curd will thicken markedly over the next several hours (I always make mine at least a day ahead so that it’s beautifully thick and the flavors nicely amalgamated). You can refrigerate for at least a week.