Mix the eggs with the sugar, the crème fraîche, the
juice of 2 lemons and the rind of 1 lemon. Put in the microwave at 700
Watt, 30 seconds at the time, until the sauce thickens. Stir in between.
You can also heat the sauce on a very low fire, stir well and be careful
not to cook. Au bain marie gives a better result, but is more time consuming.