You will really need an ice-cream maker to achieve a smooth result. As always with home-made ice-cream, ideally eat it within 24 hours of freezing.
Start by making the lemon curd: put the eggs, butter, caster sugar and the lemon juice and zest in a heavy-based pan and cook gently over a low heat, stirring, until the mixture coats the back of the spoon.
Leave to cool until hand-hot, then whisk in the thick plain yoghurt. Put into the ice-cream maker and churn until set.
Transfer to a plastic container with a lid and freeze, transferring to the fridge 15–20 minutes before serving.
© 1998 Alastair Little and Richard Whittington estate. All rights reserved.