150 ml sweet sherry or Marsala
Thinly pared rind of 1/2 lemon
Put all the ingredients in a basin over
a pan of hot water. Whisk with an electric beater until the sauce is
foamy. Do not allow to boil. If the mixture is becoming too hot,
remove the bowl from the pan and whisk to cool. Remove the lemon rind
and serve straight away.