200g caster sugar (superfine)
grated zest and juice of 3 lemons (be sure to get unwaxed)
4 egg yolks
In a heat proof bowl place all the ingredients except the egg yolks. Stand the bowl over a pan of simmering water, just like when you're melting chocolate! After a few minutes the butter will melt and then you need to start whisking it until it's completely smooth.
Here's where the directions get a little unclear. It says to add the egg yolks and to whisk vigorously for about 10 minutes until it begins to thicken. It doesn't tell you to take it off the heat, but I felt I should to not cook eggs. Then while whisking I put it back on a low heat and it started to thicken a little bit. I went ahead and poured it into my prepared jars and hoped for the best.