1) Combine 140g butter, 112g caster sugar and the lemon juice in a medium saucepan. Bring the mixture to boil over medium heat.
2) Blend the egg yolks with the remaining caster sugar in a medium bowl, using a whisk. Temper the eggs by slowly adding one third of the boiling mixture to the eggs, stirring constantly.
3) Return the egg mixture to the saucepan, over low heat, and stir the mixture until it boils. Whisk in the lemon zest and remaining butter and remove from the heat.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore we cannot make any representation as to the results.