Mix together sugar and butter. Incorporate eggs slowly. Fold in flour and salt last. Rest. Roll out with rolling pin. Line your tart mould.
Mix all together until a smooth consistency.
Pipe into tart base and bake at 160°C for 30 minutes.
Boil Juices. Mix eggs and sugar. Mix in hot juices and return to the boil. Take off heat, when warm, whisk in soft butter. Set in the fridge for a 6 hours, pipe on top of tart base. Garnish with fresh lime zest.