How to Make It
Beat yolks in a heat- proof bowl (preferably copper) until combined. Add sugar and salt, whisking constantly, until combined.
Pour wine into yolk mixture, and whisk until sugar is dissolved, about 30 seconds.
Heat mixture over a saucepan of barely simmering water, whisking vigorously to incorporate air into mixture.
Whisk until custard is warm, tripled in volume, and dragging the whisk across it leaves a ribbon on the surface, 8 to 9 minutes. Remove from heat. Serve immediately, or whisk over an ice bath until cooled.