This recipe is for altitudes of 5,000 up to 10,000 feet. If baking at 10,000 feet, add 5 tablespoons sifted cake flour.
Have all ingredients at room temperature, 68┬░ to 70┬░F, except for the eggs, which should be refrigerated until needed. Preheat the oven to 350┬░F. Grease and flour one 10-inch fluted tube or Bundt pan.
Resift twice and return to the sifter:
21 tablespoons sifted cake flour
Combine in a medium bowl and beat on high speed until thick and pale yellow, 2 to 3 minutes:
6 large egg yolks
1/2 cup sugar
1/2 teaspoon salt
1 1/2 tablespoons water
1 teaspoon vanilla
In a large bowl, beat on medium speed until soft peaks form:
6 large egg whites
1/4 teaspoon cream of tartar
Gradually add, beating on high speed:
1/2 cup sugar
Beat until the peaks are almost stiff but not dry. Use a rubber spatula to fold one-quarter of the egg whites into the egg yolk mixture, then scrape the mixture back into the bowl with the remaining whites and fold together. Sift one-quarter of the flour over the mixture at a time and fold in just until incorporated. Fold in:
1 tablespoon grated lemon zest
1 1/2 tablespoons fresh lemon juice
Scrape the batter into the pan and spread evenly. Bake until a toothpick inserted in the center comes out clean, about 35 minutes. Let cool in the pan on a rack for 5 minutes. Rotate and tap the pan against the counter to loosen the cake on all sides. Invert onto the rack and let cool completely.
