In a large stainless steel bowl whip the egg yolks with sugar until pale and light. Add wine, place bowl over a pot of gently simmering water and continue whisking vigorously. Keep moving the whisk around the bowl so it cooks evenly.
The eggs will foam up and increase in volume. When they look rich and dense and retain the shape of the whisk for a few seconds it is done. Spoon into serving glasses.