Combine first four ingredients in top of a double boiler. Cook over simmering water, stirring constantly, until butter melts. Gradually stir about 1/4 of hot mixture into egg yolks. Return egg yolks to hot mixture; continue to stir until thickened. Remove from heat; cool, cover and refrigerate. (Will last approximately two weeks.)
Fold in 1/2 cup sour cream or whipped cream to 1 cup Lemon Curd. Fill shells.
May be purchased or made from pie crust recipe. Put into tart-size pans.
Yield: 3-1/2 cups curd
Cajun Country -- New Iberia, Louisiana