Melt butter in small saucepan
Beat egg yolks, add lime juice, heavy cream, salt and pepper and mix well
Add hot butter to egg mixture in tablespoon at a time, mix well before adding the next tablespoon of butter
Return mixture to saucepan, over low heat stir constantly for 30 seconds till thickens and remove from heat
Boil a pot of water and add vinegar
Crack egg in a small bowl, the pour egg into the boiling water
Cook for about 3-4 minutes till egg white solidifies
Remove egg from water with a slotted spoon, try not to get the foam
Place on croissant or English muffin, pour sauce over