zest and juice of 3 lemons
225 g caster sugar
150 g butter
2 egg yolks
Put the zest, juice, sugar and butter into a bowl over a pan of simmering water.
Stir until the butter and sugar have dissolved. Beat the eggs together lightly, and sieve into the lime mixture. Stir continuously, until the mixture has thickened enough to coat the back of a spoon.
Pour into a clean bowl and leave to cool.