1/2 cup sugar
1 tablespoon finely grated orange zest
1/2 vanilla bean, split and scraped, pod reserved for another use
8 large egg yolks
1/2 cup Vin Santo or other sweet white dessert wine
Pinch of sea salt

Rub together sugar, zest, and vanilla seeds in a medium heatproof bowl using your fingers. Add yolks. Whisk until pale and creamy. Whisk in Vin Santo and salt. Set bowl over a pan of simmering water, and whisk until mixture thickens and doubles in volume, about 10 minutes. Serve warm.