Cream of tartar
grated rind of
Sift the flour 4 times. Beat yolks of eggs until light and thick. Gradually add 1/2 of the sugar, the lemon rind and vanilla. Beat the whites until stiff and add the cream of tartar and the remaining sugar. Combine the egg mixtures. Add salt to flour and fold into the egg mixture lightly. Pour into an ungreased pan with center tube. Bake at 325-F for 1 hour. Source:
Pennsylvania Dutch Cook Book - Fine Old Recipes, Culinary Arts Press, 1936.