1tbsplemon zestor however much you get from your lemons
1/2cupbuttercut into small pieces
Hands-off, perfectly smooth lemon curd (takes a little longer)
Bring about 2 inches of water to a simmer in a medium saucepan. Add the butter and sugar to a 2-cup Pyrex measuring cup, and sit the measuring cup in your saucepan with the water.
Melt the butter and sugar together in the Pyrex while you zest and juice your lemons. When the butter mixture is melted, add the lemon juice and zest.
Whisk your eggs and egg yolks in a medium bowl and slowly add the lemon-butter mixture while whisking. Adding the hot liquid to the eggs rather than the other way around tempers the eggs, keeping them perfectly smooth so you don't make scrambled eggs!
After that, it's easy peasy! Put the whole mixture back in the Pyrex, set it in your simmering water, and cook for about 20 minutes or until it's thickened to a thin pudding consistency. You don't have to whisk constantly - just every couple minutes to make sure nothing is sticking to the bottom or sides. It's very hands-off.
Strain through a fine mesh sieve, if desired. This will remove the lemon zest as well as any bits of egg that didn't fully incorporate.
Refrigerate a couple hours or overnight, until cold and thick.
Faster results, constant whisking, but less smooth
Whisk together sugar, lemon juice, zest, eggs, and yolks in a small or medium non-reactive saucepan (don't use aluminum, or it will make your curd taste metallic). Add in butter pieces.
Heat over medium, whisking frequently, until butter is melted and curd thickens. This will take about 10-15 minutes. It may take a little while before you start to see a difference, but once it starts to thicken, it will thicken fairly quickly. Remove from heat when it coats the back of a spoon and has the consistency of a thin custard.
If desired, strain through a fine mesh sieve. This will remove the zest and any little bits of egg that may not have fully incorporated.
Chill in the refrigerator for a couple hours or until cold and thick.