Since we want to keep the cake as light and airy as possible, use superfine sugar. If you do not have this in your kitchen, place 2 cups of granulated sugar into a food processor or blender and process for about 2 minutes.
2 cups sifted superfine sugar
1 1/3 cups sifted cake flour
1 1/2 cups egg whites, at room temperature (10 to 12 eggs)
1/2 teaspoon sea salt
1 1/2 teaspoons cream of tartar
3/4 teaspoon vanilla extract
Zest from 2 lemons (about 1 1/2 teaspoons)
Powdered sugar, whipped cream and berries for serving
Heat the oven to 350 degrees F.
Add 1/2 cup of the sugar and the flour to a fine mesh strainer set over a bowl. Sift then repeat 3 more times.
Add the egg whites, salt and cream of tarter to the bowl of a stand mixer fitted with the whisk attachment. Beat on high speed until the egg whites make firm peaks, 1 to 2 minutes.
Turn the mixer to medium speed then slowly sprinkle in the remaining 1 and 1/2 cups of sugar. Continue to beat until the egg whites are thick and shiny, 3 to 4 minutes. Add the vanilla and lemon zest then whisk another minute.
Switch to a rubber spatula then sift about 1/4 of the flour mixture over the egg whites and fold it into the eggs. Repeat this process, by sifting and folding another 1/4 of the flour mixture until all of the flour is incorporated.
Spoon the batter into an ungreased 10-inch tube pan and smooth the top. Bake until the cake springs back when lightly touched, 35 to 40 minutes. Remove the cake from the oven and turn the pan upside down and place on a cooling rack until cool.
When cool remove the cake from the pan and serve dusted with powdered sugar on top.