2 lemons, thinly sliced
3 lemons, zest and juice
1 lemon, juice only
few mint sprigs
100²µ/3½´Ç³ú caster sugar
260g/9oz caster sugar, plus extra for dusting
30g/1oz icing sugar
120²µ/4½´Ç³ú self-raising flour
1 vanilla pod
knob of salted butter
8 free-range eggs, separated
1 tbsp mascarpone
2 tbsp Greek-style yoghurt