Irish Daffodil Cake with Lemon Sauce

Yellow batter:
3/4 cups sifted cake flour
3/4 teaspoon baking powder
6 egg yolks
2 1/2 tablespoons lemon juice
1 tablespoon cold water
1/2 cup granulated sugar

Sift cake flour and baking powder together six times. Beat the egg yolks with lemon juice and water until thick, about 5 minutes. Gradually beat in the granulated sugar. Sift a fourth of the flour mixture at a time over the egg mixture; fold in.

White batter:
1/2 cup sifted cake flour
1/2 cup sifted powdered sugar
6 egg whites at room temperature
1/2 teaspoon cream of tartar
1/2 teaspoon vanilla
1/8 teaspoon salt
1/2 cup granulated sugar

powdered sugar(optional, for decorating purpose)

Sift cake flour and powdered sugar together six times. Beat egg whites until frothy. Add cream of tartar, vanilla, and salt. Beat until soft peaks form. Gradually beat in the granulated sugar. Sift a fourth of the flour mixture at a time over the egg mixture; fold in.

Alternately spoon yellow and white mixtures into an ungreased 9 or 10 inch tube pan. Bake at 170C for 35 to 40 minutes. Invert and cool. Dust the cake with powdered sugar and serve with lemon sauce. ** (Sometimes, I put the yellow mixture at the bottom and the white one on the top. Just to be fun!)

Lemon Sauce:
1/2 cup granulated sugar
1 tablespoon corn starch
1 cup boiling water
1/2 cup fresh lemon juice
1 teaspoon lemon zest
2 tablespoons unsalted butter
few grains salt (optional)

In a medium saucepan, mix together sugar and corn starch. Gradually add boiling water. Boil five minutes. Remove from heat and add fresh lemon juice, zest, butter, and salt.