To make the yuzu curd, whisk the yuzu chung, lemon juice, egg and egg yolk, the sugar and a pinch of salt together in a heatproof bowl set over a pan of simmering water until opaque and thick enough to coat the back of a spoon (ensure the bowl doesn’t touch the water). Remove from heat and whisk in the butter, a few pieces at a time, until fully incorporated. Set aside to cool completely, then chill until thickened slightly.
