Sift cake flour and salt together 2 times.
Combine lemon juice, lemon rind, water and egg yolks. Beat with a rotary beater until very thick. Add sugar a tablespoon at a time, beating thoroughly after each addition.
Sift dry ingredients into egg mixture gradually, folding in carefully.
Beat egg whites until stiff but not dry and fold over into batter, handling gently. Pour batter into ungreased 9-inch tube pan. Bake in a 325-degree oven for 60 to 70 minutes
Invert pan and cool for about an hour. You can serve it unfrosted, or cut into two layers, fill and frost and serve.
Blend together sugar, cornstarch, salt, and water. Cook until thick and smooth, stirring constantly. Add a little of the hot mixture to slightly beaten egg yolks; mix well and return to the remainder of the mixture. Cook over low heat about two minutes, stirring constantly. Remove from heat. Add lemon rind and lemon juice, cool. Spread between cake layers.
Beat egg whites until stiff but not dry. Add sugar gradually, beating until meringue forms peaks. Place cake on wire rack. Cover completely with meringue and bake in 450-degree oven until light brown, about 4 minutes.