Greek Lemon Cake

Ingredients:

3 cups cake flour
1 teaspoon baking soda
1/4 teaspoon salt
6 eggs
2 cups white sugar
1 cup butter, softened
2 teaspoons grated lemon zest
2 tablespoons lemon juice
1 cup plain yogurt

Preparation: 

Put oven to 175 degrees C. Grease one 12 inch tube pan.
Sift the flour, baking soda, and salt together.
  In a large bowl beat the egg whites until soft peaks form. Gradually add 1/3 cup of the sugar, beating until stiff glossy peaks form.
Cream butter or margarine, 1 cups sugar, egg yolks, lemon zest, and lemon juice together until fluffy.  Add flour mixture alternately with the yogurt to the egg yolk mixture. Fold in the egg whites and pour the batter.
Bake at 175 degrees C for 55 to 70 minutes. Let cake cool in pan for 10 minutes, then turn out onto a rack to finish cooling.