1/4 c  Flour
1 c  Sugar
1/4 ts Salt
1/3 c  Water
2    Egg Yolks, Beaten
2 ts Lemon Rind, Grated
1 ts Butter
1/4 c  Lemon Juice

Blend flour, sugar and salt in a saucepan; add water, stir until smooth.
Place over moderate heat, stir constantly until thick and clear. (7-8 min.)
Beat egg yolks, add a little hot mixture, beat thoroughly, return to
saucepan, stir vigorously; and cook another 2 min. Remove from heat. Blend
in rind and butter, then lemon juice. Cool. From Meta Givens Modern
Encyclopedia of Cooking.